236 CEPHALOPODA. 



1. Oviposition and the Constitution of the Egg. 



The egg of a Cephalopod, before it is mature and at the time of 

 oviposition, is surrounded by a protective envelope which, in the 

 different forms, may assume very various shapes. A large number 

 of eggs are usually laid at one spot, forming a large mass of spawn. 



In Sepia, the eggs constituting the mass are distinct from one 

 another. Each of them is surrounded by a compact, spindle-shaped, 

 black capsule of leathery consistency which, at one end, runs out 

 into a process, by means of which the eggs are attached close to one 

 another to some firm object. The egg-capsules attain about the 

 size of a hazel nut. In Rossia and Sepiola * also, the eggs are laid 

 separately and are attached to some object or else to each other, 

 but the envelope is less thick and is even transparent (Sepiola). 

 The eggs of Loligo, on the contrary, are laid in gelatinous tubes, 

 each tube containing a large number (in Loligo vulgaris, as many 

 as eighty or more). The tubes are attached by one end to some firm 

 substratum. As they stand out from their point of attachment 

 radially, they form a kind of tassel. Such large tassels are found 

 attached to plants, pieces of wood, stones, etc. 



The eggs composing a mass of spawn, resembling Cephalopodan 

 sjjawn — dredged by Gkenacher off the Cape de Verde Islands and 

 attributed by Steenstkup to one of the Teuthidae (i.e., to a form 

 something like Ommastrephes, No. 14), are also surrounded by a 

 gelatinous mass, but are not contained in distinct tubes. This spawn 

 forms a gelatinous mass 75 cm. long and 15 cm. thick which 

 resembles a sausage. Within the gelatinous cover, the violet-coloured 

 spherical eggs are arranged in fairly regular spiral coils, their number 

 amounting to thousands. Each egg, as in Loligo, is surrounded by 

 a firm envelope. A similar envelope which must be regarded as the 

 chorion (p. 246) also surrounds the eggs of the Octopoda. 



In Octopus and Argonauta, the chorion of the oval egg is drawn 

 out into a stalk. The stalks of a number of eggs become connected 



* According to Steenstrup (No. 42), the ontogeny of Sepiola as given by 

 various authors (P. van Beneden, Metschnikofp, Ussow) refers rather to a 

 species of Loligo : further obscurity being due to the fact that the masses of 

 spawn found and investigated have been attributed to Cephalopods to which 

 they did not belong. Egg-masses produced by Loligo vulgaris, a Myopsid, are 

 said to have been ascribed to Ommastrephes sagittatus, a form belonging to 

 the group of the Oigopsida. This led to the inaccurate conclusion that forms 

 remote from one another in systematic position showed great similarity in 

 their development. According to Steenstrup, this resemblance in develop- 

 ment is due rather to the fact that they all belong to the genus Loligo, and 

 theoretical conclusions founded on this similarity would thus be of no value. 



