REPORT ON THE TUNICATA. 295 



Diplosoma gelatinosum, Milne-Edwards. 



Didemnum gelatinosunit M -Edw., " Observations," etc., p 79. 



Colonies of this species were found attached to Algae and 

 stones at low water mark, and in tidal pools, at Port Erin, 

 and at Bay-ny-Carrickey, Isle of Man. 



Diplosoma crystallinum, Giard. 



Pseudodidemnum crystallinum, Giard, Recherches, etc., p. 650. 



This species was obtained attached to Zoophytes, Poly- 

 zoa, Algae, and in some cases to stones, off Port Erin and 

 Port St. Mary, Isle of Man. It is very much more delicate 

 and more transparent than the last species, and the Ascidio- 

 zooids are less conspicuous in the investing mass. 



A good deal of variation is present in the Manx specimens 

 as to the pigment-cells in the test. In some cases, a large 

 amount of yellow pigment is present ; while in other cases 

 the test is free from pigment, and is then perfectly clear and 

 transparent. 



ASCIDI/E SIMPLICES. 



Family. — Clavelinid^. 



I use this family in the sense of Milne-Edwards' Ascidiae 

 Sociales, including Perophora as well as Clavelina, and 

 allied forms. For reasons which I have given elsewhere,* 

 I regard Clavelina as more nearly allied to the Simple 

 than to the Compound Ascidians ; by most continental 

 authors, however, the Clavelinidae are regarded as belonging 

 to the Synascidiae. In a paper t published recently. Dr. 

 Sluiter, of Batavia, has brought forward additional evidence 

 supporting my view that the genus Ecteinascidia forms a 

 transition from Clavelina to the Ascidiidae, and that the 



* "Challenger" Exp. Report ; Zool., Tunicata, Part I, 1882. 

 f Ueber einige einfachen Ascidien, &c., Natuurkundig Tijdschrift v. 

 Nederlandsch- Indie, Band, xlv, p 160, 1885. 



