Sponges from the Atlantic Ocean. 467 



or less sharp, fringed edge. These spicules rapidly diminish 

 in size with their distance from the margin of the wall ; so that 

 very soon they altogether disappear ; whether by incorj)oration 

 with the older and general structure or by absorption 1 am not 

 able to state. Where they are not present, the margin of the 

 wall presents a roumled form. Occasionally the larger ones 

 on the edge are inflated or spined at one or both extremities ; 

 but this appears to be an abnormal state, their staple form 

 being acerate. Colour whitish yellow. The " oval" appear- 

 ance of the summit of the tubercle when seen from above is 

 an optical delusion which is corrected by the lateral view. 



There are a few fragments of this sponge in the same jar 

 as the foregoing species (viz. that bearing the numbers " 2,5, 

 75, 374 fathoms ") ; and they average 2 inches in diameter by 

 ^ of an inch in thickness. These, which consist chieflv of h'a'nf/ 

 portions or portions which were taken alive and afterwards 

 preserved in spirit and water, bear all the characters above 

 mentioned, including the presence of the acerate spicules, which 

 are very almndant where the living border of a new layer can 

 be traced growing over the surface of a previously dead or 

 denuded surface of the frond. The fragments appear to have 

 been broken off by the dredge from the head of a living spe- 

 cimen, as the fractured parts are not worn by attrition. 



I have given a short account of a very large specimen of 

 this species, viz. Azorica Pfeiferw ('Annals,' 1873, vol. xii. 

 p. 442), which, together with a slightly smaller one of the 

 same kind, was presented to the British Museum by Madame 

 Ida Pfeiffer. 



It appears from Schmidt's figures (Atlant. Spongienf. pi. iii. 

 fig. 2 ii:c.) to be very like his Leiodermatium Li/nceus • but here 

 the oscule3 were on the outer side, which is the reverse of what 

 they are in Azorica Pfeifera", and the reverse of what gene- 

 rally obtains in sponges, where the concave or tubular por- 

 tion receives the vents. Schmidt's diagnosis o^ Leiodermatium 

 (smooth-skin), too, is: — "In der Oberflachenschicht liegen 

 kcine isolirten Kieselkorper " {op. cit. p. 21). 8o the ])rescnce 

 of the isolated acerate spicules above mentioned, although con- 

 fined to the sarcode towards the growing margin of Azorica 

 Pfeifcro', is also opposed to this. Hence it becomes doubtful 

 whether Hchm'idt^s Leiodermatium Lf/nceus ia Azorica Pfeiferce; 

 but there is no doubt that the latter does not agree with his 

 diagnosis, although the " isolated acerates " are only ])artially 

 present — that is, about the growing portion. Then, in the 

 Lithistina, where there are " isolirte Kieselkorper" on the 

 surface, they all disa])pear from it as the latter becomes incor- 

 poratel with the internal or older structure, and thus trans- 



