gg GEODIA MESOTRIAENA. 



Geodia mesotriaena, sp. nov. 



pachana, var. nov. 

 Plate 21, fig. 1; Plate 23. figs. 3, 5, 6. 8, 9; Plate 24, figs. 3, 5, 9. 



microana, var. nov. 



Plate 23, figs. 1-2, Plate 24, figs. 2, 0, 7, 10-13, 16, 19. 21. 



megana, var. nov. 



Plate 21. figs. 2-G; Plate 22, figs. 1-10; Plate 23, figs. 4, 7, 10-25; Plate 24. figs. 1. 4. 8, 14, 15, 17, 



18. 20. 22-32; Plate 25, figs. 1-11. 



I establish this species for three sponges, a complete thy specimen, a com- 

 l)letc spirit specimen, and some fragments, also preserved in spirit. These 

 specimens were collected at Stations 2909, 2942, 2958, off the coast of southern 

 California. Their spicule-fur is composed of large and conspicuous mesotriaenes 

 # and to this the specific name refers. Although these three specimens are similar 

 enough to be considered as the same species, each possesses peculiar characters 

 so that it seems advisable to separate them as varieties. The most conspicuous 

 differences between them are those of their anatriaenes. In the specimen from 

 Station 2909, var. pachana, the anatriaene-cladomes are small and stout; in 

 that from Station 2942, var. microana, the anatriaene-cladomes are small and 

 slender; and in that from Station 2958, var. megana, the anatriaene-cladomes are 

 large. 



The s])ecimen of var. microana is cake shaped and appears as a low and broad 

 inverted cone with bulging sides, 72 mm. high, with largest and smallest hori- 

 zontal diametei-s of 116 and 104 mm. respectively. The upper side, forming the 

 base of the cone, is quite flat, the lower side, forming its apex, rounded. Judg- 

 ing from the fragments of var. megana this was similar (Plate 21, fig. 2) but larger, 

 probably as much as 200 mm. in maximum diameter. The specimen of var. 

 pachana (Plate 21, fig. 1) is relatively broader than the other two and somewhat 

 similar to a plane-convex lens with vertical axis and flat ujijier face. It is 230 

 mm. in horizontal diameter and 120 mm. high. The basal part, the apex of the 

 lower convex side wherewith the sponge was attached, has been torn off — in its 

 complete state, with this apex, its height may have been 140 mm. 



The colour of var. microana is yellow, that of var. megana brown and that 

 of var. pachana dirty olive-brown on the surface and a lighter, yellowish brown 

 in the interior. The first two are in spirit. The last is dr}\ 



On the upper face and on the sides depressions are met with. In the smaller 

 specimens (var. miavana and var. megana) these are few in number, large parts 

 of the surface being without any trace of them (Plate 21, fig. 2). In the larger 



