280 BUCCINID^. 



informs me that on the coast of Caithness, throughout 

 the winter, the Purpura assemble in clusters low down 

 towards the sea, where they are left dry at spring tides 

 only, and that they also huddle together in crevices of 

 the rocks ; he could hardly find a single individual in 

 the usual summer habitat in the coiu'se of an hour^s walk 

 which he took along the shore in the middle of March. 

 Their voracity and cannibal propensities begin at a very 

 early age. Dr. Carpenter has shown (and his ol^serva- 

 tions are confirmed by Mr. Busk, Professor Huxley, 

 and Dr. Dyster) that the embryo of P. lapillus, before 

 it leaves the nidus or capsule, swallows the yelk around 

 it. The observations of Claparede on the development 

 of Neritina coincide with those of Carpenter as to Pur- 

 pura. Koren and Danielssen, however, give a difi'erent 

 account of the matter. They say that each capsule is 

 at first hermetically closed, and filled with a liquid, 

 which is as transparent as water, viscous, and resembles 

 the white of a bird's e^^ ; in this liquid are enveloped 

 a mass of eggs, 60 or even more ; in process of growth 

 these eggs agglomerate, and form from 20 to 40 embryos, 

 which are developed in the same manner as those of 

 Buccinum undatum, the shell taking the shape of a 

 Nautilus, and that at the end of the 9th or 10th week, 

 and not before, the fry quit the capsule. The latter 

 then bm'sts at the top, and shows an open split. The 

 capsule adheres to the rock, sometimes to Balani or to 

 the shells of other Purpurea, by a short and narrow 

 stalk, which is connected with a membranous and broad 

 base ; each is distinct and separate. They are slightly 

 striated across. At one time they were classed among 

 the Polypes, and called Hydra triticea ; Ellis gave them 

 the name of sea-cups. Mr. Peach has furnished some 

 interesting particulars of the embryogeny of P. lapillus. 



