438 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Lundbeck has shown, 1902 (pp. 101-102), that three classes of 

 diancistra coexist in the same individual in H. bowerbank'U differ- 

 ing greatly in size though only slightly in shape (1902 p. 18). Top- 

 sent, 1904, likewise finds very small and medium sized diancistra 

 along with the large ones in several species. Lundbeck has, more- 

 over, examined, 1902 (p. 103), H. esperioides and finds that the 

 small diancistra recorded by Ridley and Dendy cannot be young 

 forms, but represent a distinct class of spicule. 



I refer the Albatross specimen to a variety, instead of to the type, 

 because of its difference in form, smaller size of styles, smaller size 

 of sigmas, and absence of the very small diancistra. 



The Albatross sponge is an amorphous mass 13 by 8 cm., incrust- 

 ing and surrounding a broken mollusk shell ; thickness of sponge 25 

 mm. and less. Surface is not conulose. but as in the type is con- 

 spicuously reticular to the eye, except over the large ectosomal 

 spaces: there are several such, the largest 9 mm. in diameter, roofed 

 in by the nonreticular translucent dermal membrane; some of these 

 open by oscula, 3-5 mm. in diameter; it is uncertain whether they 

 are all efferent. The resemblance in surface appearance to the type 

 (see Ridley and Dendy) is thus close. 



The sponge is whitish brown, compressible and easily broken ; 

 greatly excavated by canals of considerable size. In general the 

 choanosome reaches the dermal membrane in the shape of narrow 

 trabeculae, between which lie the small subdermal chambers. The 

 trabeculae divide up the dermal membrane into polygonal areas, and 

 thus give to the surface the reticular appearance perceptible to the 

 eye. The dermal membrane is uniformly pierced by closely set 

 pores, 90-180 [jl in diameter, although the reticular appearance of 

 the surface suggests the existence of " pore-areas " separated by 

 aporous tracts. In the nonreticular areas of dermal membrane roof- 

 ing in the larger ectosomal spaces pores occur, as well as elsewhere. 



The internal skeletal framework consists of abundant compact 

 spiculo-fibers, looser tracts, and scattered spicules, all crossing in 

 every direction without order. Spicule tracts that are radial to the 

 surface are distinguishable in the superficial part of the sponge. 

 The fibers reach a thickness of 160 [k. Spongin not perceptible; if 

 present at all, there can only be a very little of it. The dermal 

 skeleton in general is an irregular reticulum quite as in Ridley and 

 Dendv's figure, 1887 (pi. 17, fig. 12). Over the larger ectosomal 

 spaces where the dermal membrane is not reticular to the eye, the 

 spicule tracts are either more confusedly arranged or else broken up 

 into scattered spicules. 



The styles agree with those of the type except that they are 

 smaller, 470-500 by 12 \i. The large diancistra are like those of 

 the type and of about same size; they commonly have a length of 



