526 THE ARGONAUT. 



distinctly, and the processes, extending from the head, are 

 become more elongated. Here, however, I was obliged 

 to stop, this being the most perfectly-developed embryo 

 I could find among the ova. The eggs in contact with 

 the front part of the discoidal portion of the shell, where 

 the egg-mass is attached by the glutinous threads, are the 

 most forward in their development, while those in the 

 posterior part of the chamber, are much less matured. 

 Poli's account of the development of the ova is as follows: 

 "Ova quae in primis eburneo candore nitebant, tenui veluti 

 nubecula perfundebantur; mox bina puncta subrubentia 

 hinc et illinc sese conspicienda praebuerunt in regione 

 oculorum eaque deinceps protuberantia evadebant. His 

 perfectis, aliud punctum eodem colore perfusum prope ovi 

 fastigium oculos supereminens apparuit : quod quidem 

 oris embrionem satis luculenter ostendebat."* 



There is considerable difference between the animals of 

 Argonauta tuberculosa and A. hians. In the A. tuberculosa 

 the sac-like mantle is more ovoid and elongated ; the head 

 is narrower; the infundibulum is broader, shorter, and fur- 

 nished, at the upper and anterior extremity, with two 

 conical prolongations ; the eyes are considerably larger, 

 and slightly more prominent; the tentacular arms are 

 much shorter in comparison, and of greater width, more 

 particularly at their basal portions. The suckers are much 

 larger, more prominent, and placed closer together. This 

 species varies also considerably in colour from A. hians. 

 The extremities of the brachia are marbled with deep red- 

 brown ; and, in the other parts, are covered with large 



* Test, utriusq. Sicilise, &c., p. 10. 



