546 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



Budding" and Statoblasts in Tunicates.* — Marc de Selys-Long- 

 champs describes in Stolonica socialk, one of the Polystyelidfe, a peculiar 

 mode of budding. On stolons, which are diverticula of the body-wall, 

 buds are isolated which become statoblasts. Their further development 

 does not give rise to a colony properly so called, for the ascidiozoids 

 which emerge are independent, and it is only secondarily that they 

 combine more or less intimately. No actual continuity was observed 

 between the individuals. It may be that in spring there is direct 

 budding, without the formation of statoblasts. 



INVERTEBRATA. 



MoUusca. 



y. Gastropoda. 



Structure of Runcino.f — Guiseppe Colosi gives an account of the 

 macroscopic and microscopic structure of R. mlaritana sp. n. — a 

 Tectibranch Gastropod. He demonstrates the presence of a gastric 

 valve, a gastric gland, an unpaired " liver " with a single opening into 

 the intestine, and a secondary kidney. The genital apparatus is quite 

 unique. It is necessary to make within TectilDranchs a special section, 

 Kuncinidea. 



5. Lamellibranchiata. 



Larva of Oyster.^ — J. L. Dantan has studied the early stages in 

 the development of Ostrea edulis. The eggs develop in the pallial 

 cavity, but the parent should not be called viviparous. The larva 

 shows a neural plate, a preoral crown of cilia, a postoral wreath, and 

 a medio-anterior zone. At the entrance of the gullet there are two 

 ectodermic buccal glands. The stomach is divided by a constriction 

 into a cardiac and a pyloric pouch. There are two hepatic vesicles. 

 The larvte ingest microscopic particles in the pallial cavity. Below the 

 large cells of the preoral crown of cilia there are four nerve-masses 

 united by very delicate nerves to the neural plate. The muscular 

 system is much more developed than has been described. The fibrils 

 are striated, but in contraction they assume the vermicular appearance 

 believed to be characteristic of smooth muscle. The upper part of the 

 larva corresponds to the cephalic portion of a trochophore ; the ciliary 

 apparatus and the nervous system are essentially the same in oyster- 

 larva and trochophore ; they both possess head-kidneys, and probably 

 other transitory larval organs, the anal vesicles. 



* Bull. Sec. Zool. France, sli. (1916) pp. 6-15 (5 figs.). 



t Mem. E. Accad. Sci. Torino, Ixvi. (1915) pp. 1-35 (18 figs.). 



X Comptes Rendus, clxiii. (1916) pp. 239-42. 



