112 



PORIFERA. III. 



1904. H. raphigeua Tops. Resultats des camp, scient. du Prince de Monaco, Fasc. XXV, 192, PI. XV, 

 fig. 7. (Leptosia). 



— obtusata Tops, ibid., 193, PI. XV, fig. 6. {Leptosia). 



— acerata Tops, ibid., 193, PL XV, fig. 5. (Leptosia). 



1( p^ _ tcnuissima Dendy, Rep. on the Pearl Oyster Fishery of the Gulf of Manaar, III, 169, PI. XI, 

 fig. 5. (Myxilla). 



— areolata Thiele, Zool. Jahrb. 1905, 452, Taf. 31, Fig. 23, 68 a— d. 

 1906. — land/era Tops. Bull, du Mus. d'hist. nat. 560. (Leptosia). 



The number of species seems thus at present to be about seventy; this is already a large 

 number and there is reason to believe, that many more species will be described in the future. 

 Earlier Expeditions paid often but little attention to the insignificant crusts, which is the shape of 

 most Hymedesmia species; it is first in the work of Topsent from 1904 that a greater number of 

 incrusting species of various genera is recorded, and the author says expressly, that this fact is due 

 to the care with which he examined stones, corals etc. brought home. The Ingolf Expedition laid 

 the greatest stress on procuring all small and incrusting sponges, and hence our material is very rich. 

 Under these circumstances when the number of species must be expected to increase in the future 

 to some degree, it is of the greatest importance, that the new species are described thoroughly, and 

 the spicules ought always to be figured, so that the affinities of the species can be judged. I shall 

 therefore try to give here an analytical table of all the above enumerated species; this table is of 

 course only an attempt, and I do not think that a species can be definitely determined only by its 

 aid, but I think however it may be useful. 



Table of the Species of Hymedesmia. 



1. Microsclera present 



— No microsclera 



2. Microsclera only chelse arcuatse (sometimes transformed to spined rods) 



Microsclera chelse arcuatae together with sigmata, or sigmata alone or rhaphides 



3. The chelae of common shape 



— The chelae spined or quite transformed 



4. The dermal spicules genuine strongyla 



— The dermal spicules of other forms, at all events not quite genuine strongyla. 



5. The acanthostyli not divided into two groups 



— The acanthostyli somewhat distinctly divided into two groups 



6. The dermal strongyla more or less distinctly polytylote 



— The dermal strongyla not, or not distinctly, polytylote 



7. The chelae somewhat strongly curved, 0-028— 0-050 mm , the acanthostyli with blunt 



spines on the head Koehleri Tops. 



— The chelse less strongly curved 8. 



8. The chelse with somewhat long, free alse, 0-045— 0-054 mm lacera 



— The chelse smaller, somewhat like palmate chelse 9- 



9. The acanthostyli strongly spined, especially at the head, chelse 0-033— 0-038 mm . storea 



— The acanthostyli less strongly spined, chelae 0-028 mm lamina 



2 

 59 



3 

 45 



4 



43 



5 

 21 



6, 



13 



7 

 10, 



