26 C. 0. Wbitman 



around the central zone a ring composed of four Segments. Each of 

 these Segments is a cell.« 



8. Dieyemennea Eledones Wag. Figs. 44 — 47, PI. 4. 



Found in Eledone moschata Leach iusually in com- 

 pany with Dicyetna mo sc ha tum) and Eledone Aldro- 

 vandi Delle Ghiaie. 



Calotte enneamerous, conoidal, permanently orthot- 

 ropal, wider than the body. 



The 4 equal triangulär-pyramidal propolars always 

 much smaller than the 5 sub-equal prismoidal metapo- 

 lars. The propolars are 2 dorsal and 2 ventral; the 

 metapolars 3 dorsal (l median and 2 lateral) and 2 ven- 

 tral. The cephalic enlargement formed chiefly by the 

 calotte, but, to some extent, by the 2 lateral parapolars. 

 The ectodermal cells, beginning with the parapolars, 

 arranged in 7 alternating pairs. 



Verruciform cells none. 



Total number of ectodermal cells 23. 



Length 5 — 7 mm. 



The occurrence of this species in Eledone moschata has already 

 been detailed in the account of D. moschatum. I bave found it in ten 

 of the twelve E. Aldrovandi which I have examined, and always unac- 

 companied, except by Benedenia elegans or B. coronata. Thus the fre- 

 quency of its occurrence may be estimated at 6 : 30 in E. moschata^ 

 and 25 : 30 in E. Aldrovandi. 



I have been unable to detect any peculiarity in individuals obtained 

 from one host not found in those from the other; and in uo instance 

 have I met with anything that could raise a doubt as to their specific 

 identity. 



As this species is found in at least two diflferent Eledones , and has 

 not thus far been found in any other genus of the Cephalopods, the 

 name D. Eledones Wagener, is very appropriate, and for this, as well 

 as other reasons before mentioned, has been preferred to D. Wageneri^ 

 proposed later by Van Beneden. 



In gracefulness of form and transparency this species is excelled 

 by none; and in length, by D. macrocephalum alone. In these respects 

 it agrees nearly with D. gracile of Se2na officinalis (fig. 4S) . 



The form of the calotte, which diöers in a most marked manner 



