366 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



do not occur, they have been rubbed off. In each pit that was opened, 

 a small commensal ophiuroid was found. The wall of the pit is 

 smooth. It doubtless is studded with pores in the expanded state of 

 the sponge, but in the actual specimen is aporous. Nevertheless in 

 spots what seemed to be traces of closed pores were visible. As in 

 the type specimen, small protriaenes were seen in places to project 

 obliquely over the wall of the pit. 



As in the type no oscula, apart from the poriferous pits, were to 

 be seen. The pits are probably therefore in part efferent, in part 

 afferent. 



The specimen agrees with Hentschel's in being incrusted with 

 shelly debris, etc. ; in the dense character of the ectosome, which, 

 however, does not include a fibrous stratum; in the arrangement 

 of the megascleres, ectosomal brushes of smaller spicules being ab- 

 sent. The distinctness of the radial skeletal bundles is lessened 

 somewhat by the presence of radial megascleres scattered between 

 them. The sponge is heavy and very compact, all the canals being- 

 small. The ectosome measured about 500 [x in thickness and no sub- 

 dermal cavities could be seen. 



The Albatross specimen is much larger than that from which 

 Hentschel's pieces came, and may be looked on as an older specimen. 

 It comes from a different locality. One would expect to find, then, 

 spicule measurements different from HentschePs, and in fact the 

 spicules are considerably larger. 



Oxeas, in general equiended, tapering, 2.5 mm. by 16 jx to 6 mm. 

 by 50 jx; the chief radial spicule and chief spicule in fringe of 

 poriferous pit. Small equiended oxeas, commonly 180-200 by 3-4 p, 

 are scattered in some abundance through the parenchyma. They 

 perhaps represent young stages. 



Protriaenes are almost absent over the general surface of the 

 sponge. The very few seen had short, stout clads 36-40 [x long, rhab- 

 dome long and 16-30 jx thick near cladome. Protriaenes are common 

 in the fringes of the pits. Here they have a long, tapering rhab- 

 dome, reaching several millimeters in length, about 16 [x thick near 

 cladome; clads 50-70 by 12 [x. Smaller, slenderer protriaenes pro- 

 ject obliquely from the lateral walls of the pits, in places. The 

 protriaenes in the type specimen are very slender. 



Anatriaenes are common, along with the radial oxeas. The cla- 

 domes of many lie in the ectosome, but there are also many that 

 project beyond the surface of the sponge about 1-2 mm. The rhab- 

 dome is 12 a thick near the cladome, then tapering to a hair-like 

 thickness, about 7 mm. long, often somewhat sinuous where wrapped 

 round the large oxeas. Clads in a typical spicule measure 56 by 

 12 [jl. The anatriaenes in the type specimen are very slender. 



