M. T. Thorell on the Species of the Argulidse. 443 



This extremely short and meagre description is accompanied 

 by a coarse woodcut representing the animal from beneath, but 

 in which we can distinguish neither antennae, " sting," nor shape 

 of the mouth-tube. There seem to be no comb-like teeth on the 

 hinder foot-jaws. The tail is described in the following words : — 

 " Then [on the abdomen] follow two short folia, covered by two 

 others, each of them nearly as long and as broad as the exposed 

 part of the abdomen." The species undoubtedly stands near 

 A.funduli, but seems to be distinguished by a somewhat longer 

 head-shield, a longer and more deeply cloven tail, with more 

 pointed lobes and smaller sucking-cups. Whether the feet 

 possess flagella [gissel] or not, is not to be learnt from either 

 description or figures. 



This Argulus is, according to Gould, found on the " Alewife," 

 which he identifies with the European Alosa vulgaris. Probably 

 the fish in question was an Alosa tyrannus, Dekay, which, ac- 

 cording to Valenciennes *, is the Alewife of the United States. 



In ' Silliman's Journal,' (1839) vol. xxxvi. p. 393, under the 

 title " New Species of Argulus; notice from Dr. T. W. Harris," 

 we find the following remarks : — " It may interest some of your 

 readers to be informed of the discovery of another species of 

 Argulus in this country. It was found in the gills of a herring 

 caught upon Brighton Bridge, from Charles River, during the 

 month of June last. It differs from Argulus foliaceu^ of Europe, 

 and from the species described in a former number of your 

 Journal, vol. xxxiv. p. 225t, in the size and form of the body and 

 in the shortness of the legs. Having presented the specimen to 

 Dr. A. A. Gould for description, I shall not attempt to anticipate 

 him by giving a detailed account of its specific characters at this 

 time." 



It is undoubtedly A. alosa which is here alluded to; for 

 Gould says, with reference to this specimen, that it was presented 

 to him by Dr. T. W. Harris, who found it on the branchiae of the 

 "Alewife," which fish in America, like the Alosa vulgaris with us, 

 is often confounded under the general name of " herring " or 

 *' sill." Gould has described no other species of Argulus. That 

 the species difi'ers from A. foliaceus in the shortness of the legs, 

 is a mistake. See the diagnosis. 



12. A. elongatus, Hell. 



Syn. Argulus elongatus. Heller, Sitzungsber. d. Kais. Akad. d. Wissensch., 

 Math.-Naturwissensch. CI., (1857) xxv. p. 106, taf. 3. figg. 1-4. 



Scutum cephalicum minimum, longitudine trunci, inverse sub- 



* Cuvier et Valenciennes, 'Histoire Naturelle de3 Polssons,* (1847) 

 torn. XX. p. 421. 

 t This probably means vol. xiai. p. 297, where A. catostomi, Dana, is 



