1881.] THE SURVEY OF H.M.S. * ALERT.' 11/ 



ESPERIA MAGELLANICA, sp. n. (Plate X. fig. 5.) 



Massive^ subcyliudrical. Surface and interior coloured by cells 

 containing a dark pigment. Dermis fragile, with a coarse skeletal 

 network. Main skeleton composed of a central irregular compact 

 mcshwork, which sends ramifying and anastomosing fibres to the 

 dermis. Fibres of main and dermal skeleton stout, composed of 

 parallel spicula with a minimum of sarcodc. Skeleton-spicules of 

 one form only, viz. spiuulate, with a very slightlj'^ marked oval 

 head ; length "4615 to ".544 millini., breadth -01207 niillim. Paren- 

 chyma pale yellow to ochreous brown when dry, dirty white in spirit. 

 Flesh-spicnles of two forms, viz. : — (i.) inequianchorate with the 

 large palm about -j% of the total length of the spicule, and its lower 

 angles turned upwards and inwards, length •0444 to •05384 raillim., 

 scattered ; and (ii.) minute acerate, generally in bundles of two to 

 four, sharply pointed, length ^0444 to '0634, breadth about '001055 

 millim., scarce. 



Examined. In si^irit, in dried state, and mounted in balsam. 



External Characters '. 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 extre- 

 mity, 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 ; inspirit 

 grey, or dirty-white (in the dried specimens ranging from yellowish 

 white to an ochreous brown). Surface entirely covered with mammi- 

 form papillae, 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 milliais. in diameter, 

 probably much larger in life. Texture delicate, very readily com- 

 pressible. Pores ? 



Minute 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 loose spiculo-fibre, with polygonal meshes 

 from ^25 to •o millim. in diameter, tympanized by a very pale brown 

 sarcode more or 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, occa- 

 sionally 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. 



Hah. Sandy Point, 7-10 fathoms; bottom, dead Balani, some of 

 which are still, together with a good-sized Terebratula, embedded 

 in its base. 



Seven dry specimens from Otter Island, Patagonia, representing 

 ' These refer to the spa-it speeiinen, except where otherwise stated. 



