192 CTENOPIIOR^. Part II. 



Notwithstanding Lesson's assertion to the contrary, I see no reason ^\h\ the 

 genns Neis Zci-s-. shouhl Ijc removed from the inunediato vicinity of the Beroids 

 proper and bronght into close rehitionship with Mnemia. Every word in the 

 description of that beautiful Acaleph bearing upon its structure, coincides with the 

 impression made by the figure published in the Zoologie de la Coquille, PI. XVI. 

 F/'ff. 2, in strengthening the conviction that Neis belongs to the Ctenophora; 

 Eurystom*. It has the wide mouth and truncated oral margin, and the vascular 

 reticulation throughout the spherosome ; and if the anterior and posterior sphero- 

 meres seem to project like the lobes of the Ctenophora) Lobata>, a careful analysis 

 of the description, compared with the figure, will show at once that the inter- 

 ambulacral space between these spheromeres alone differs from the rest of the 

 surface of the liody in being more brightly colored, but that they do not fonn 

 a lobe-like expansion, nor are there tentacular tubes or auricles, w^hicli exist in 

 all the Mnemiidiw While 1 am convinced, therefore, that Neis belongs to the 

 Eurystom*, I am not quite so sure that it should not l^e considered as the type 

 of a distinct fomily, the Neisid.e Less. ; for Lesson expressly states that the abactinal 

 pole is not only much more compressed than the actinal, but also deeply emarginate, 

 and thus giving the whole body a wedge-shaped and heart-shaped form, which can 

 scarcely be the result of the same arrangement of the motory cells as exists in 

 the Beroids proper, the body of which is thmner at the actinal pole. According 

 to his figure and description there is also a marked difference in the disposition 

 of the rows of locomotive flappers, which are nearly equal in the true Beroids ; 

 while in Neis the anterior and posterior pairs are niucli longer than the lateral 

 pairs, and converge towards the circumscribed area, the lateral ones converging 

 towards one another. If these traits are not in themselves family characters, they 

 seem at least to indicate family differences. Gegenljaur erroneously refers Neis to 

 the fiimily of the Cydippida?. 



The Beroids proper as a fiimily would then eml:)race the species thus far referred 

 to the genera Beroe, Idya, Cydalisia, Medea, and Pandora, subject to a critical 

 revision of their closer affinities. The names Beroa) and Beroida^, it is true, were 

 first introduced by Goldfass and Rang to designate the whole order of Ctenophora", 

 and then limited by Eschscholtz and Lesson to the Cteuophora^ Eurystoma3 ; but 

 if Neis and Idya dentata Less, constitute distinct families, the family of Beroid.e 

 will in the end only embrace those Ctenophoraj Eurystoma; whose body is evenly 

 compressed laterally and provided with nearly equal rows of locomotive flappers,^ 

 the regular forms of which arise from the even distribution of the radiating and 



' In all regular rouiuk'J or slightly coiiipressed flappers is only nominal. A searching comparison 

 Ctenophorw, the equalily ot the rows of locomotive discloses in all these Acalephs, even in the most 



