"Esperia magellanica, sp. n. (Plate X. fig.5)
Massive, subcylindrical. Surface and interior coloured by cells containing dark pigment. Dermis fragile, with a coarse skeletal network. Main skeleton composed of a central irregular compact meshwork, which send ramifying and anastomosing fibres to the dermis. Fibres of main and dermal skeleton stout, composed of parallel specula with a minimum of sarcode. Skeleton-spicules of one form only, viz. spinulate, with a very slightly marked oval head; length •4615 to •544 millim., breadth •01267 millim. Parenchyma pale yellows to ochreous brown when dry, dirty white in spirit. Flesh-spicules of two forms, viz.:--(i.) inequianchorate with the large palm about 6/13 of the total length of the spicule, and its lower angles turned upwardws and inwards, length •0444 to •0634, breadth about •001055 millim., scarce.
Examined. In spirit, in dried state, and mounted in balsam.
External Characters1 . Form irregularly cylindrical, rounded off rapidly below to a narrow base of attachment, and provided above with a slight neck at about 30 millims. From the superior extremity, where it is also rounded off. Below the neck the greatest diameter is about 60 millims., above it about 45 millims.; total length 120 millims. Colour in life very variable, yellow or green; in spirit grey, or dirty-white (in the dried speciemens ranging from yellowish white to an ochreous brown). Surface entirely covered with mammiform papillæ, from 3 to 6 millims. in greatest diameter, often coalescing into ridges; provided at the superior extremity with two circular vent-openings, respectively 7 and 8 millims. in diameter, probably much larger in life. Texture delicate, very readily compressible. Pores?
Minutes Structure of Surface. Surface covered by a fragile dermis, of the thickness and texture (when wet) of blotting-paper, composed of a single layer of more or less spiculo-fibre, with polygonal meshes from •25 to •5 millim. in diameter, tympanized by a very pale brown sarcode more of less interspersed with loose spicules and greenish-brown granular cells, sometimes having the centre occupied by a dark patch of pigment.
The minute acerates occur in bundles of two to four, occasionally scattered; they are straight and sharply pointed at both ends. They are found at the sides of the dermal and main skeleton-fibres. They are of scarce occurrence; and for that reason and from the need of an exceptionally good light for finding them, they constitute an inconvenient character for reference. Probably they invariably occur in the place of tricurvates in Esperia, where these are absent.
Hab. Sandy Point, 7-10 fathoms; bottom, dead Balani, some of which are still, together with a good-sized Terebratula, embedded in its base.
Seven specimens from Otter Island, Patagonia, representing three specimens, were already in the Museum collection, and are evidently pieces of those mentioned by Dr. Cunningham at p.481 of his ‘Notes on the Natural History of the Strait of Magellan.’ The following are their chief characters, arranged for comparison with those of the type specimen. It cannot, unfortunately, be determined which pieces formed part of the same original specimen.
Subspinulate spicule.
Inequianchorate spicule.
Bundles of Acerates.
Other characters.
No. 1
Shape as in type; •497 mm. long by •01267.
Shape as in type; •04434 mm. long
Scares; •057 mm. long.
Surface ridged rather than papillose.
No. 2
Ditto
Shape as in type; •05384 mm. long
(Curved, very scares; •07842 mm. long?)
Surface do.
No. 3
Ditto
Shape as in type; •04434 mm. long
?
Surface do; vents?
No. 4
Shape as in type; •4615 mm. by •01267.
Shape as in type; •05067 mm. long.
Very scarce, generally scattered; •06334 mm. long.
Surface papillose in one part, ridged in another.
No. 5 (most of surface gone).
As in No. 1.
As in No. 1
Very scarce; •042339 mm. long.
Surface the same; a large internal cavity. Apparently 2 vents.
No. 6
Shape as in type; •488 mm. by •01267.
Shape as in type; •047506 mm. long.
Very scarce; •044339 mm. long.
Surface ridged. Vents 3?
No. 7
As in No. 1.
Shape as in type; •05067 mm. long.
Ditto.
Surface ridged and papillose. Vents 2?
Type specimen from Sandy Pt.
•544 by •01267 mm.
•0475 mm. long.
Scarce; •057 mm. long.
Surface mostly papillose. Vents 2.
All possess an abundance of the characteristic dark pigment, but concentrated at the centres of well-defined cells, whereas in the spirit specimen from Magellan’s Straits it is generally, though not always, scattered over the cells.
It is very probable that the wrinkled or ridged character presented by the dermis of most of the dried specimens is due to the fact of their having been dried. In all cases except that of the extraordinarily broad specimen No. 6, external characters of shape, surface-reticulation, and colour agree very closely in all the dried specimens, and must be almost, if not quite, identical with those which would be presented by the spirit specimen if it were dried.
Obs. This Sponge belongs to the section of Esperia which is devoid of bihamate flesh-spicules. It is to be wished that a distinct genus were formed for the reception of the numerous forms which belong to it. Possibly Rhapidotheca, Kent, may ultimately be found to satisfy the requirements of the case (cf. Mr. Carter’s remarks in the Journ. Roy. Micr. Soc. ii. p.498); but until the questions which are suggested by the description of the type species of that genus are settled, it will be well to adhere to the more comprehensive term Esperia for these forms.
The nearest allies of this Sponge, of which intelligible descriptions of specimens are available, appear to be:---
Spinulate spicule.
Inequianchorate.
Acerates.
Esperia nodosa, Schmidt, Adr. Meer. Suppl. i. p.33 (Adriatic).
•4117 by •011085 mm.
•0577 mm.
•057 mm.
E. bowerbank, id. Adr. Meer. P.55 (Adriatic).
About the same as preceding.
•06334 mm.
Ditto.
E. tunicate, id. ibid. (Adriatic)
•399 by •0095
•05384 mm.
•0475 mm.
E. rhopalophora and E. intermedia, Schmidt, from the North Atlantic, may perhaps prove, when more fully described, to come near this species. Rhaphidotheca affinis, Carter, from off the north of Scotland, differs but slightly from it in the forms of its spicules; but their sizes are greater.
For details of appearance in life see Dr. Cunningham’s work on the Straits of Magellan above mentioned."
(Ridley, 1881)
