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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 81 



strongylote and sometimes oxeote. Tetracts show in boiled-out 

 preparations but are not readily found in sections. 



Reinofrks. — Cyamon and Trikentrion are in a little group by them- 

 selves, very distinct from other sponges. Practically all the species 

 of Cyamon hitherto described have had their distinctive (polyactine) 

 spicules entirely and finely spined, the other spicules styles. In 

 contrast, Trikentnon has its polyactine spicules usually triacts and 

 with only one ray spined, but that coarsely so and with diactines as 

 accompanying spicules. C. neon is a very distinct type, answering 

 the definition of Cyamon but being very different from any of the 

 genus. On paper it reads a bit like Trikentrion -jidbellifonms 

 Hentschel (1912, p. 377), from the East Indies, but the illustrations 



Figure 65. — Cyamon neon de Laubenfels : A, X300; others, X80. D, fraction of 



total length of spicule shown 



show great differences. The comparison is mentioned only because 

 flabeUiformis shows us a species with both monacts and diacts, with 

 the polyactines mostly triacts and only one ray spined; these are 

 coarse spines, however, and there are numerous differences in spicule 

 size, and general architecture of the sponge. 



Order HAPLOSCLERINA Topsent 



Family SPONGILLIDAE Gray 

 Genus SPONGILLA Lamarck 



SPONGILLA LACUSTRIS (Linnaeus) 



Spongia lacustris Linnaeus, 1759, p. 1348. 

 Sponffilla lacustris Lamakck, 1815. 



Material examined.— V.^.'^M. No. 21516; B.M. Nos. 29.10.31.1, 

 29.9.30.3. These bright green digitate fresh-water sponges were 

 collected by Prof. AV. K. Fisher, of Stanford University, at Lake 

 Tahoe, elevation 2,040 meters, August, 1925. 



