CYDIPPID.E. 29 



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

 advancing age. 



Fig. S6. Fig. 37. 



This species is exceedingly common in Eastport harbor, dm-ing the 

 month of September. 



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

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



Museum diagram No. 3 after Alex. Agassiz. 



Family CYDIPPID^ Gegenb. {rest. Ag.) 



Cydippiclw Gegexb. Archiv f. Nat., 185G, I. p. lOtJ. 

 Callianiridm EscH. {p. p.) Syst. d. Aeal., p. 21. 1829. 

 Cydippidw Agass. Cont. Nat. Hist. U. S., III. p. 293. 1860. 



PLEUROBRACHIA Flem. 



Pleurohrachia Flem. Phil. Zobl., 11. p. 612. 

 Ct/dippe EscH. Syst. der Acal, p. 29. 1829. 

 Cydippe Le8S. Zooph. Acal., p. 104. 1843. 

 Pleurohrachia Agass. Mem. Am. Acad., IV. 1849, p. .SI 4. 

 Pleurohrachia Agass. Cont. Nat. Hist. U. S., III. p. 203. 1860. 



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



Fig. 37. Young Mertensia about in tlie 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. 



