CYDIPPID^. 



29 



flappers. The pigment-spots become smaller and less conspicuous with 

 advancing: atfe. 



This species is exceedingly common in Eastport harbor, during the ' 

 month of September. 



Arctic Ocean (Mertens, Scoresby) ; Baffin's Bay (Pabricius) ; Massa- 

 chusetts Bay, and Eastport, Me. (A. Agassiz). 



Museum diagram No. 3 after Alex. Agassiz. 



Family CYDIPPID^ Gegenb. {rest Ag.) 



Cydippidce Gegenb. Archiv f. Nat., 1856, 1, p. 196. 

 Callianirida: EscH. (p. p.) Syst. d. Acal., p. 21. 1829. 

 Cydippidce Agass. Cout. Nat. Hist. U. S., m. p. 293. 1860. 



PLEUEOBRACHIA Flem. 



Pleurobrachia Flem. Phil. Zool., II. p. 612. 

 Cydippe Esch. Syst. der Aoal., p. 29. 1829. 

 Cydippe Less. Zooph. Acal., p. 104. 1843. 

 PleurobracMa Agass. Mem. Am. Acad., IV. 1849, p. 314. 

 Pleurobrachia Agass. Cont. Nat. Hist. U. S., HI. p. 203. 1860. 



Fig. 36. Still further advanced Mertensia, seen from the broad side. 



Fig. 37. Young Mertensia about in the same condition as that of the preceding figure, seen 

 from the narrow side. The main branches of the ambulacral system have lost the character of 

 pouches. 



