177 



In the Stomatopoda the eye is present in both Squilla mantis and 

 Squilla Desmarestii. It is borne on an elongated stalk which extends 

 anteriorly from the brain, at a point midway between the optic nerves 

 to the inner surface of the shell. Bellonci^ (1878) in his description 

 of the brain oî Squilla mantis entirely overlooked this structure though 

 CI au s 4 had mentioned its presence in the young adult of Gonodac- 

 tylus in 1871. 



Only two Schizopods have been examined , one a large and the 

 other a small species of Euphausia. The eye present in both, and 

 easily seen from the exterior, is located between the compound eyes 

 and is directed dorsally. 



In the Macrura I have found the eye in the Carididae in Alpheus 

 dentipes , where it is very evident, in Nika edulis and in Peneus mem- 

 hranaceus and Peneus caramote. — In the Astacidae it occurs in Ho- 

 marus vulgaris. — In the Palinuridae it occurs in Palinurus vulgaris 

 and Scyllarus arctus. — In the Galatheidae it occurs in Munida rugosa 

 and Galathea squamifera. — In the Thalassinidae in Gebia littoralis 

 and Callianassa subterranea and in the Paguridae in Eupagurus Pri- 

 deauxii. 



I have not examined examples of the Sergestidae , Polychelidae 

 and Hippidae, though the organ is probably present in these groups. 



The only Brachyuran examined , a species of Homola , gave the 

 same general result as the Macrurans, though the organ was somewhat 

 less intensely pigmented. 



In a later paper, dealing with the central nervous septum of the 

 Crustacea, figures and a more detailed description of this organ will 

 he given. 



Stazione Zoologica, Naples. April 2, 1894. 



3. Protandric Hermaphroditism in Myzostoma. 



By William Morton Wheeler, Ph.D. , Chicago University. 



eingeg. 5. April 1894. 



In the following preliminary note I would call attention to cer- 

 tain peculiarities in the sexual conditions of the Myzostomids. My re- 

 sults were obtained from a study of the four Mediterranean species: 

 Myzostoma glabrum Leuck., M. cirriferum Leuck., M. alatum v. Graff 

 and M. pulvinar v. Graff. The two former occur on the common An- 



3 G. Bellonci, Morfologia del Sistema Nervoso Centrale della Squilla man- 

 tis. Ann. del Mus. Civico di Storia Naturale di Genova. Voi. XII. p. 518. 



* C. Claus, Die Metamorphose der Squilliden. Göttinger Abhandlungen, 1871. 

 XVI. p. 4. 



