144 Miscellaneous. 



consequently to the mouth ; this is the highest one : the other, less 

 prominent and placed laterally, gives passage to the water which 

 traverses the branchiae, to the residues of digestion, and to the pro- 

 ducts of reproduction. 



Between these two orifices a small opaque-white nucleus may be 

 distinguished through the tissue, with delicate filaments issuing from 

 it : this is the nervous ganglion. 



Thus Chevreulius is undoubtedly an Ascidian, but it is a bivalve 

 Ascidian, of which the test is divided into two parts moveable upon 

 each other, as in the Acephala ; and the Ascidia themselves must be 

 arranged in two series — one for those in which the external envelope 

 is a true little leather bottle with two apertures, the other for those 

 in which the test, divided into two parts by a broad horizontal cleft, 

 becomes bivalve. 



Having met with Chevreulius for the first time in the waters of 

 Calle, I have named it C. cal/ensis. It lives at great depths (GO, 80, 

 or 100 fathoms), and belongs to the fauna of the coralligenous zone. 



In conclusion, the author remarks upon the interest attaching to 

 the discovery of Chevreulius, as an Ascidian with an upper and 

 lower valve, in connexion with the relation existing between the 

 Tunicata and Brachiopoda. — Comptes Rendus, June 19, 1865, 

 p. I 264. 



On some singular Organs appended to the Feet of certain Crustacea. 

 By MM. Claus and Sars. 



Professor Claus (Zeitschr. wiss. Zool. xiii. p. 422) and Professor 

 Sars (Videnskabsselskab. Forhandl. 1863) have independently in- 

 vestigated the Schizopod Crustacea of the family Euphausidse with 

 regard to the singular organs already alluded to by Dana, Semper, 

 and Krover, and regarded by Semper as eyes, and by Kroyer as 

 auditory organs. These are spherical organs, of a reddish colour, 

 situated at the base of several of the thoracic legs and of the first 

 four pairs of abdominal appendages. Both the authors above men- 

 tioned have demonstrated the correctness of Semper's view, although, 

 besides these pedal eyes, the animals possess the two large com- 

 pound eyes common to all Decapoda. Each of the thoracic and 

 abdominal eyes receives a special nerve from the ventral ganglionic 

 chain. The organ itself is a spherical bulb, moved by special mus- 

 cles ; and in it may be distinguished a crystalline lens, a vitreous 

 body, a pigment-layer, and a retina of complex structure. The 

 existence of a crystalline lens distinct from the cornea is very striking, 

 as remarked by M. Sars; for in other Crustacea no true crystalline 

 exists, its function being performed by the thickened and inflated 

 cornea. According to M. Claus, the position of the four pairs of 

 abdominal eyes is very remarkable : the first pair looks forwards, 

 the last pair backwards, and the two intermediate pairs downwards. 

 — Bibl. Univ. May 1865, Bull. Scient. p. 63. 



