PEGANTHA LAEVIS. 99 



P. laevis is entirely colorless ; the disc hyaline, the endodermic system 

 nearly opaque. 



This species differs from all of the forms described by Haeckel ('79) 

 in form of gonads, number of otocysts, number of tentacles, and lack of 

 exumbrellar sculpture. It is, on the other hand, very closely related to the 

 P. dacti/letra described by Maas ('93, p. 47) from the Tropical Atlantic. As 

 already pointed out, the gonads of the two forms are very similar, the slight 

 differences between his account and the present specimens being easily 

 explicable as the result of different stages in growth. The number of oto- 

 cysts (five to seven per lappet) and the pentagonal form of the marginal 

 lappets likewise agree in the two species. There is an apparent difference in 

 the number of tentacles, Maas recording only sixteen for P. dactz/letra ; but I 

 doubt whether this indicates anything more than individual variation, since 

 one of the two adult specimens in the present collection has only eighteen, 

 and since Maas had only a single specimen of P. dactyletra. Of no more impor- 

 tance is the apparent difference in size, for the " Plankton " specimen was 

 described by Maas after preservation (with osmic acid), and therefore the 

 diameter which he gives, ,30 mm., is no doubt smaller than the Medusa 

 actually was in life. The only important distinction seems to be the pres- 

 ence of a well-marked exumbrellar sculpture in P. dadi/letra, and its entire 

 absence in P. laevis. It is, of course, impossible to state whether this feature 

 is constant until more specimens, particularly of P. dactyletra, are examined ; 

 but since sculpture is an important character in other members of the genus, 

 it seems best to recognize the present form as a distinct species, at least for 

 the present. 



The capture of a specimen of this species by the " Albatross " among the 

 Hawaiian Islands shows that it, like P. triloba, is of very general distribu- 

 tion throughout the Eastern Pacific. 



Pegafdlm laevis, as already noted (p. 9), shows the early stages in a type 

 of internal budding very similar to that which I have described (p. 62) for 

 Gunina peregrina. In the present species, however, the process takes place, 

 not in the gastric cavity proper, as in Cunina, but in the peripheral canals 

 (ring canal alone ?). In a budding individual the oral wall of the ring canal 

 bears irregular ridges and swellings (PI. 27, fig. 1), which vary in form. On 

 sections it is seen that these ridges are purely endodermic structures, the 

 ectoderm taking no part in their formation ; but here, as in Cunina, I must 

 acknowledge the possibility of a migration into the budding region of amoe- 



