46 DEVELOPMENT OF THE CEPHALOPODA. 



Cuthbert Collingwood (Jour. Linn. Soc., xi, 1873), encoun- 

 tered (in 1S70), floating upon the surface of the Atlantic Ocean, 

 in lat. 37 N. and long. 28. W., a gelatinous object, somewhat 

 cylindrical in form, about 2 feet long and 4 or f> inches in 

 diameter, and containing cephalopodous ova arranged in clusters 

 and single rows. The young animals were very active, and in 

 fact were all discharged a short time after the nidus had been 

 secured. It is impossible to ascertain positively at present to 

 which genus this curious form belongs, though evidently the 

 animal is finned and pelagic. The whole oviposit is here united 

 within a single gelatinous covering instead of being aggregated 

 into sausage-shaped masses each filled with embryos as in Loligo, 

 or in separate eggs as in Sepia. I give a figure of one of these 

 ova, magnified 24 diameters. A similar floating- mass was 

 obtained ]by Dr. H. Grenadier, at the Cape Verd Islands, in 

 January, 1*72; it was nearly 2-.") feet long by (i inches in 

 diameter. I give figures both of nidus and embryo, extracted 

 from his elaborate and valuable paper on the development of this 

 interesting form ('/ell. Il-V.s.s. ZooL, xxiv, 1874). 



Quoy and Gaimard (Ann. $c. Nal., x\. IS.'IO) discovered near 

 the Moluccas, a cylindrical nidimental mass, :> feet long and 

 G to 8 inches diameter, composed of cephalopodous eggs placed 

 in double rows on a ribbon, the circumvolutions of which, with 

 margins overlapping, formed the cylindrical shape. 1 figure this 

 mass, as well as a portion of the ribbon, showing the disposition 

 of the eggs, as well as one of the latter, magnified. The ribbon 

 does not materially differ from the small portion discovered by 

 d'Orbigny in ()</<>/>/<* nn'mbr(in.u<-i>nx, and which lie lias erro- 

 neously figured as a portion of the nidus of that animal (see my 

 Fig. 6,' PI. 20). 



Devrlojti/K'ii/ of UK' Ct'i>li(il<>p<>d<i. 



"In the dibranchiates the yolk undergoes partial division, and 

 the blastoderm (yolk sac) formed upon face of if by the smaller 

 blastomeres, spreads gradually over flu 1 whole ovum, enclosing 

 the larger and more slowly dividing blastomeres. The mantle 

 makes its appearance as an elevated patch in the centre of the 

 blastoderm, whilst the future arms appeal- as symmetrically dis- 



