Isopod Genua Leptochelia. 157 



misunderstood. This is partly to be explained by the circum- 

 stance that Dana's writings are often almost as inaccessible as 

 they are celebrated. Leptochelia, with its type species 

 minuta, was first described in the ' American Journal of 

 Science,' vol. viii. p. 425, 1849. A fuller account, was given 

 in the ' Crustacea of the U.S. Exploring Expedition, 1852- 

 5-V wherein the remark is made that "Tanais Eduoardsii of 

 Kibyer (Tids. iv. 1842) is of this genus." Figures of the 

 type species were published in the Atlas in 1855. 



It must be borne in mind that, besides the extremely 

 slender and elongate first gnathopods, the type species has 

 very long upper antennae, in which the second joint is unusually 

 elongate as well as the first, and biramous uropods, in which 

 the small outer branch has two joints. Dana says : — " Caudal 

 stylets as long as abdomen, longer branch six-jointed, shorter 

 minute, two- or three-jointed." The appearance of a third 

 joint may have been produced by the crossing or apical 

 meeting of two setules. In the Tanais Edivardsii of Kroyer, 

 to which Dana refers, the gnathopods are stouter, the second 

 joint of the upper antennae is by Krbyer's account not more 

 than a quarter as long as the first, and the outer branch of 

 the uropod is distinctly one-jointed. When Bate and West- 

 wood in 1866 adopt the genus Leptochelia for Krbyer's 

 species, they declare that the uropods are " unibranched," 

 distinguishing the genus from Paratanais by the fact that the 

 pleon " has only a single branch to the caudal pair of pleopoda 

 attached to the sixth segment ; " and again, in their specific 

 description, they repeat that " the posterior or caudal pair of 

 pleopoda consist of a single multiarticular^ branch." They 

 give not the slightest intimation that both the authors to 

 whom they refer had described the appendages in question as 

 double-branched. In 1878 the late Oscar Harger, in his 

 1 Report on the Marine Isopoda of New England and adjacent 

 waters,' makes Dana's Paratanais a synonym of Leptochelia 

 supposing the former genus merely to represent the females 

 of the latter, but at the same time being well aware of the 

 structure of the uropods in the various species which he 

 groups under the same generic name ; so that he says in 

 regard to the uropods, " the outer ramus may also consist of 

 more than one segment." He remarks, too, that the type 

 species, a L. minuta, possesses all the characters of Para- 

 tanais that could occur in the male." This way of putting 

 it was not sufficiently direct to warn other writers of the 

 differences between Dana's species and the Tanais Edioardsii 

 of Kroyer, with which Dana had himself compared it. 

 Accordingly in 1880, and again in 1S86, Professor G. O. 



