52 THE MEDUSAE. 



Even if this supposed difference in development does not exist, there 

 is another character, of considerable value, which does distinguish the two 

 species and this is the number of otocysts per marginal lappet. It is true that 

 Maas considers this feature of no systematic importance, because in C. odonaria, 

 as well as in C parasitica an increase, with development, of from one to three per 

 lappet has been observed (McCrady, '57 ; Brooks, '86 ; Miiller, '6r) ; but 

 this number (three) appears from the studies of Brooks ('86), Mayer (: 00''), 

 and Maas himself (: 05) to be the normal limit which is reached in C. octonaria ; 

 for although Maas observed occasional lappets with four octocysts, it is 

 likely, since three have so usually been observed in adult specimens of this 

 species, that a greater number is, as Maas suggests, a sporadic variation. 

 In G. jmrasitica, however, Metschnikoff has observed stages in develop- 

 ment up to the formation of five per lappet, and suggests the possibility of 

 a still further increase; while Haeckel had already observed seven per lappet 

 (C. poli/gonia). In neither of these species is there any peripheral canal 

 system (Wilson, '87, p. 99 ; Maas, : 05"). Browne (: 06) has described re- 

 cently another Cunoctantha, C. foivleri, from the Bay of Biscay, but his speci- 

 men, which showed external budding, had no gonads, so that its final 

 disposition must remain doubtful. 



To these species there must now be added C. tenella, sp. nov., from the 

 present collection, in which a canal system is well developed. I do not 

 hesitate to place this species in Cunoctantha, since, though only one of the 

 specimens is sexually mature, all (seven) have eight tentacles. In view of 

 the fact that in Cunina species with and species without canals ( C. peregrina) 

 occur, and that even in one species ( C. proboscidea) one generation may have, 

 the other lack, canals (Metschnikoff, '86*; Stchelkanowzew, : 06), there is 

 nothing surprising in finding a parallel series of forms in the closely related 

 genus Cunoctantha. 



Cunoctantha octonaria McCrady. 



Cunina octonaria McCrady, '57, p. 211, pi. 12, figs. 4, 5. 



Cunoctantha octonaria Haeckel, '79, p. 316 ; Brooks, '86, p. 361, pis. 43-44 ; Maas, : 05, 



p. 67, taf. 12, figs. 77, 78, taf. 13, figs. 83-85. 

 Cunoctantha incisa Mayer, : 00'', p. 66, pi. 44, figs. 145, 146. 

 Foveolia octonaria A. Agassiz, '65, p. 51. 



Plate 14, Fig. 4; Plate 15, Figs. 5, 6; Plate 17, Figs. 3, 4, 5. 



Acapulco Harbor; many specimens, 1.5-4 mm. in diameter. 



The largest specimens (PI. 14, fig. 4), none of which are sexually mature. 



