made at Naples in the winter q/* 1871-72. 95 



.'vum, but, owing to the interest which the later development 

 also had for me and the impossibility of keeping specimens 

 alive, did not come to definite conclusions. The germinal 

 vesicle seems to disappear ; and a cap of blastodermic cells 

 appears at one pole of the egg, somewhat as in Loligo. The 

 changes in the mass of the yelk whilst this goes on are re- 

 markable, and lead to the formation of corpuscles, which appear 

 to circulate subsequently in the embryonic blood-system. I 

 can confirm (if confirmation be wanting) Professor Panceri's 

 and Pavesi's description of the heart and mouth of the cyatho- 

 zooid, and its mode of connexion with the four ascidiozooids. 

 Professor Panceri's recently published figures (Academy of 

 Naples) are excellent. The colonial muscular system described 

 by Panceri (see 'Quart. Journ. Micr. Sci.' Jan. 1873) was also 

 examined; and I repeated the experiments which he had just 

 carried out, leading to the deteimination of certain granular 

 masses on the sides of the pharynx as the phosphorescent 

 organs of Fyrosoma. 



^ginopsis was found on one occasion in some water taken 

 from the surface. The structure of the arms Avas not given by 

 Johannes Miiller so fully as examination with a no. 10 Hart- 

 nack now allows. 



Cercaria ecMnocerca w^as obtained and drawn from examina- 

 tion with the 10 immersion on several occasions. It is re- 

 markable for the flattened seta-like processes of the integument 

 of the tail. 



The Parasite of the Renal Organ of Cephalopoda. 



Dicyenia sepim and D. eledonce were first described by 

 Kolliker, Clapar^de afterwards found a species in the Eledone 

 norvegica, and referred Dicyema to the ciliate Infusoria. 

 Subsequently Guido Wagner described D. sepice and D, ele- 

 donce in more detail than his predecessors. 



There is probably no stranger parasite than the Dicyema. 

 The renal organ of most Sepice, may be said to be literally 

 made up of these organisms in all stages of growth. They 

 are clearlynot Infusoria, but adegraded form of worm, being mul- 

 ticellular in structure. They are, when typically grown, thread- 

 like bodies one third of an inch in length. There is no mouth, 

 but an axial tissue of scattered stellate cells, wdiich is clothed 

 with large epithelial scales : these are at one time all ciliated ; 

 but after full grow^th the cilia only remain about the head. 

 The head is indicated by a knob, on which the epithelial scales 

 are very regularly disposed in two series. It is rare to find a 

 large Dicyema with this head well developed — the reason being 

 that the animals are continually dividing transversely, and a 



