Miscellaneous. 71 



it is of the form A ; with the series of interior chambers it is of the 

 form B. But it is necessary to remark that, as among the Orhalinai 

 we meet, on the one hand, with large empty individuals, and, on the 

 other, with small individuals, some empty, some with interior 

 chambers, we cannot assume in this case, as has been indicated for 

 Miliolidge, an absorption of the large embryonal chamber. 



The case of the OrbaNnrn is in favour of our first hypothesis, and 

 seems to demonstrate that the dimorphism of the Poraminifera is an 

 initial character, the result of two original forms. — Gomptes Rendus, 

 April 21, 1SS4, p. 1002. 



On fJie Ascidicm Genus Rhopalca. By M. L. Roule. 



Philippi first described (Miiller's Archiv, 1843), under the name 

 of Wiopaha neapolitana, an Ascidian that he had collected in the 

 Bay of Naples, and of which he has given a short anatomical de- 

 scription, but sufficiently accurate as to most of the details of organi- 

 zation that he has noticed. In his memoir he approximated this 

 new genus Rhopalea to the GlaveUinm. Since Philippi's time, so 

 far as I know, no other naturalist has studied this curious form of 

 Ascidian ; Traustedt does not notice it in his work upon the simple 

 Ascidia of the Bay of Naples (Mittheil. aus der zool. Stat, zu Neapel, 

 1883), and Herdman (Timicata collected by the ' Challenger '), re- 

 ferring to the description given by Philippi, places it alongside of 

 Ecteinascidia, in the family Clavelinidae. 



The jRliopcdecK are very abundant on the shores of Marseilles on 

 the bottom surrounding the Zosterm, in the muddy sands collected 

 by the currents at dej^ths of from 25 to 60 metres ; hence I have 

 been enabled to observe numerous individuals and to make a regular 

 investigation of them. The body, of an average length of 8 to 10 

 millim., of a nearly pure white colour, is divided into two parts 

 — one anterior, of triangular form, free, containing the branchia, 

 and bearing the two siphons (buccal siphon with eight or nine, and 

 cloacal siphon with six papillfc) ; the other posterior, of irregular 

 form, adherent to the ground, and incrusted with debris of various 

 kinds, containing the mass of the viscera. These two parts are 

 joined together by a slender region of considerable length, through 

 which the rectum, filled with substances destined to be rejected, 

 may be distinguished ; the general aspect much resembles that of a 

 somewhat stout and very large Glavelina. 



The thick tunic is of a soft consistency around the anterior part 

 of the body, firm a.nd resistant around the posterior part. In this 

 latter region the fundamental substance of the tunic encloses nume- 

 rous vacuolar cells, while it contains none in the anterior region. 

 The dermis (mantle), which is thin, bears small muscular bundles, 

 most of which run in the direction of tho length of the body ; around 

 the siphons there also exist a certain number of annular muscular 

 bundles. Philippi erroneously regarded as a peritoneum the portion 

 of the dermis which surrounds the posterior visceral mass. The 

 fundamental web of tho branchia, the apertures of which are oval 



