some Entomostraca. 21 



tic4 penultim^ dimidium posticse apicalis non superante, setis 

 antepenultimis brevibus. Maxillipedes magni. Pedes nata- 

 torii qninti paris magni, simplices. 

 Abdomen 3-articulatum, articulo tertio duos prsecedentes longi- 

 tudine fere sequante. Seta caudalis secunda corpore longior, 

 niula. 



This species may perhaps be a young form, for the fifth pair of 

 natatory legs has very much the appearance of being immature. 

 I do not think, however, that it can be the young of any already 

 described species, as it has five cephalothoracic segments instead 

 of four, which is the common number ; and although E.pubescens 

 has, it is true, the same number, yet in that species the additional 

 segment is the posterior one, while here it is formed by the sepa- 

 ration of the head. For these reasons it cannot, I think, be con- 

 sidered as the young of the preceding species, with which it was 

 found ; besides which, it has a fifth pair of natatory legs, of which 

 I could find no trace in E. Atlantka. The shape of the head when 

 seen from above, the second pair of antennae, mandibles, first and 

 second pairs of maxillae, maxillipeds and first pair of natatory 

 legs, all very closely resemble those of the preceding species. 

 The fourth pair is rather stouter in proportion. In E. Atlantka 

 I could never find any fifth pair of natatory legs in the female, 

 but in this species they are of a considerable size, "027 inch in 

 length, and consist of a two-jointed basal part, bearing two un- 

 equal branches, each consisting of one segment, but the outer one 

 much the largest. The two inner ones are not symmetrical. The 

 abdomen is three-jointed, and the third segment is nearly as large 

 as the two first put together. 



Of this species there are only three or four specimens. They 

 were caught on the 22nd August, in 12° 21' N. Lat. and 25° 

 W. L. 



Length '065 inch. 



„ of the maxillipeds '035. 



PI. IX. figs. 1, 2. 



Undina Dance, n. sp. 



Maris. — Frons quadratus. Cephalothorax 5-articulatus, postice 

 rotundatus, articulo ultimo breviore. Antennae anticae cor- 

 pore breviores ; setis brevibus, posticd penultim4 antepenulti- 

 maque articulos non aequante. Abdomen 4-articulatum. Styli 

 caudales breves, setis quatuor plumosis. 



This species may be at once distinguished from all of Profes- 

 sor Dana's species by the front being quadrate. 



