292 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



The sponge is irregularly spheroidal with a greatest diameter of 

 65 mm., and is thus somewhat larger than any of Keller's speci- 

 mens. The aperture of the apical cloaca is 12 mm. wide ; cloaca and 

 apertures of efferent canals as in Keller's specimens (pi. 19, figs. 50, 

 51), color much the same, also consistency. 



Sections radial to surface show the features illustrated in Keller's 

 figure 56 (pi. 20) ; except that the actual surface is well preserved 

 in the Albatross specimen. Thus distal to the cladomes of the ortho- 

 triaenes is a thin layer of ectosome. The fibrous layer occupies the 

 rest of the ectosome and is about 600 [x thick. The pores, chonal 

 canals, subcortical crypts, and radial canals are all as in Keller's 

 figure, except that the actual pores are small. Flagellated chambers 

 of same size as in Keller's types. 



The megascleres have the same arrangement as in Keller's types 

 (pi. 20, fig. 56) and are of about the same size. The anatriaenes 

 differ in having a deeper cladome. The details are as follows: 



In the orthotriaenes, the rhabdome is 1 to 2.2 mm. long, 40-80 y. 

 thick below cladome; clads 135 to 210 \l long, 35 to 70 \i thick at base. 

 Orthotriaenes are abundant. Surface preparations show the clads 

 meeting or overlapping and thus surrounding angular or rounded 

 areas, often about 175 y. in diameter, in which the pores may be seen. 



In the anatriaenes, the rhabdome is 2 to 2.5 mm. long, 20-35 y. thick 

 below cladome; cladome deep or fairly deep, clads strong and 120 

 [A long. 



The larger oxeas measure about 1.5 mm. by 20-24 jjl 



In Keller's types the asters are " very small and delicate " oxyasters 

 with 7-9 rays and about 10 [x in diameter. Similar asters occur in 

 some abundance in both ectosome and choanosome of the Albatross 

 sponge. Tangential sections show that they are quite abundant at 

 the extreme surface, where they range in total diameter 8-12 p. In 

 the interior the total diameter ranges 8-16 \).. There is " no centrum." 

 the rays are very slender and even under an immersion objective 

 show no distinct terminal enlargement, although at such a magnifica- 

 tion they appear slightly roughened. 



Keller finds microspheres, about 5 ja in diameter, very abundant in 

 spots in the choanosome. Colorless spherules up to this size occur 

 also in the Albatross sponge in ectosome and choanosome, sometimes 

 scattered but often in dense groups. Appearances suggest that there 

 is perhaps some relation between such groups and the spheruliferous 

 cells mentioned below. 



Keller's sponges all contained peculiar masses of a problematical 

 nature. These formed a single and nearly continuous layer in the 

 outer part of the cortex (p. 342, pi. 20, figs. 56, 57), were spheroidal 

 or ovoidal in shape, about 100 \l in diameter, and of a dark-brown 

 color (yellowish in the figure given). Each mass is said to be a heap 



