364 HANDBOOK OF INVERTEBRATE ZOOLOGY. 



XXX.— THE DEVELOPMENT OF THE SQUID. 



(Loligo Pealii.) 



The eggs of the sea-urchin present an illustration of 

 total regular segmentation ; and those of a lamellibranch 

 illustrate total irreo;ular seo;mentation. The egf^s of the 

 squid may be examined as examples of partial segmen- 

 tation. 



The eggs of the common squid are frequently taken in 

 the trawl or dredge, and they are often found among the 

 contents of a seine Avhich has been drawn over a weedy 

 bottom. They are also found occasionally on the beach, 

 among; the sea-weeds which have been washed ashore. 

 They are contained in a cluster of elongated, spindle- 

 shaped, transparent egg-capsules, each of which contains 

 from twenty to seventy or eighty eggs. The capsules are 

 all joined to a central stem, thus forming a cluster, some- 

 thing like a bunch of grapes, and six or eight inches long. 

 Freshly-deposited eggs are not found as frequently as par- 

 tially-developed ones, and in the latter the little squid can 

 readily be seen, moving about within the egg-shell. 



The newly-laid egg is surrounded by a transparent, 

 elastic, oval egg-shell (Fig. 191, a), with an opening, the 

 micropyle, m, at one end. Outside the egg-shell is the 

 gelatinous substance of the capsule, and inside, the elon- 

 gated oval yolk floats, suspended in a transparent albumi- 

 nous fluid. At first sight the yolk appears to be homoge- 

 neous, but careful examination shows that it is filled with 

 oil drops of various sizes, and with faintly marked edges. 



Before the egg is laid the end of the yolk nearest the 

 micropyle becomes diflferent from the rest. Its oil drops 

 disappear, it becomes transparent, finely granular, and 



