1903.] FROM EAST AFRICA AND ZANZIBAR. 355 



Trippa Bergh. 



12. „ flr(?o7«j!rt. (A. (t H.). 



13. ,, monsoai, sp. n. 



Fracassa Bevgh. 



14. „ tuhercidosa. 



Hcdgerda Bergli. 



15. ",, vnlleyi, »]). n. (From the Loyalty Islands.) 



16. ,, loasinensis, sp. n. 



Kentrodoris Bergh. 



17. „ rubescens Bargh. 



riatydoris Bergh. 



18. „ eurychlaviys Bergh. 



19. „ scahra (Cuvier). 



20. „ formosa ? (A. k H.). 



21. „ e^/io«i? (A. ct H.). 



22. ,, pulchra, sp. n. 



23. „ incerta, sp. n. 



24. „ papUlata, sp. n. 



Sclerodoris Eliot, gen. n. 



25. ,, osseosa (Kelaai't). 



26. ,, tidjercidata, sp. n. 



27. ,, mino7% sp. n. 



28. „ rubra, sp. n. 



29. „ corlacea, sp. n. 



A steronotas Ehrenberg. 



30. „ hemprichi Ehrenberg. 



The Cryptobranchiate Dorids are distinguished by having 

 branchice which are completely retractile into a permanent pocket. 

 The rhinophores also are retractile into permanent pockets and 

 are perfoliate, A radula is always present. In number of 

 species they form one of the richest groups of the Nudibranchiata, 

 but they show less variety of form than the Dorididfe Phanero- 

 branchiatfe, and it is not easy to find good generic characteristics. 

 The most distinctly marked group is that consisting of the large 

 genus Chroniodoris (with more than 100 species) and some alHed 

 genera such as Casella and Ceratosoma. These possess a charac- 

 teristic shape, lip-plates, a radula with differentiated teeth, and 

 simply pinnate branchife. Well characterised genera are also 

 found in the Miamirada? {Miamira, Orodoris, Siohcerodoris) and 

 the Cadlinidc-B {Cadlina, Tyrinna). There remain the five sub- 

 families mentioned above, which agree in being usually flat and 

 oblong in form and in having a radula without a central tooth, 

 consisting of numerous laterals which are generally hamate £vnd 

 uniform, though often smaller near the rhachis and degraded or 

 denticulate at the outer end of each row. 



Anyone who describes new forms of these Dorids, however 

 much lie may disclaim any such ambitious task as a revision of 



