REPORT ON THE PTEROPODA. 



57 



SUMMARY OF THE KNOWN SPECIES OF GYMNOSOMATA. 



It will be seen from the foregoing descriptive monograph, that we now know fairly 

 well, and in the adult state, twenty-one species of Gymnosomatous Pteropoda, which are 

 divided as follows : — 



Genera. 



Dexiobranchxa, . 

 SpongiobrancJi xa, 

 Pneumonoderma, 

 Clionopsis, . 

 Notobranchxa, . 

 CHone, 

 Halopsyche, 



Species 



5 

 1 

 6 

 3 

 2 



3 

 1 



21 



Of these twenty-one species, eleven were collected by the Challenger Expedition ; 

 these eleven species belong to six of the seven known genera, the genus CHone being 

 alone wanting (for the arrangement of the species in the different genera, see the table in 

 the Introduction, p. 8). One of these genera is new {Notobranchxa), as, are also more 

 than a third of the species collected (four out of eleven). 



The eleven Challenger species were obtained at thirteen different Stations, as shown 

 in the following list ; all being collected, like all the living Pteropoda, in surface 

 gatherings. 



(ZOOL. CHALL. EXP. PART LVIII.— 1887.) 



Mmru 8 



