222 I^otes 071 North American Crustacea. 



Amphitrites probably form a distinct genus, with their large 

 eyes, prismatic hands, etc. ; but this point we have not yet 

 investigated. 



Acheloiis g^ibbesii. 



Lwpa gibhesii Stimpson, An. Lye. Nat. Hist, of N. Y., vii. 57. 



An important distinctive character in this species, which we 

 overlooked in the previous description, consists in the existence 

 of one or two shallow oblong pits or little depressed spaces, 

 with a smooth, iridescent surface, near the antero-lateral 

 margin at the penult or antepenult marginal tooth. At least 

 one of these pits is always present, and will always distinguish 

 this species from the varieties of A. s^inimanus, some of which 

 approach it quite nearly, being similar in coloration. They 

 are, also, almost always found together. 



It is found as far north as Beaufort, N.C. 



Achelous xantuiiiii, nov. sp. 



Carapax pubescent ; front and antero-lateral margins meeting in an 

 angle. Front four-toothed; teeth equally prominent; the two middle 

 ones less broad and more acute than the outer ones, and separated from 

 them by a wider space than from each other. Antero-lateral margin 

 nine-toothed, including the angle of the orbit, which is prominent, 

 protruding forward nearly as far as the frontal teeth ; posterior tooth 

 (or lateral spine) nearly three times as long as the one anterior to it. 

 Eyes of moderate size, and in great part concealed by the orbit when 

 retracted ; cornea rather less thick than the peduncle. The entire 

 lower margin of the orbit may be seen from above when the eyes are 

 retracted. Meros-joint of external maxillipeds with the anterior extre- 

 mity produced, rectangular. Chelipeds slender, pubescent ; meros 

 depressed, with the pubescence arranged on slight transverse ridges on 

 the upper surface, and the anterior margin five- or four-spined; carpus 

 and hand each two-spined. Ambulatory feet slender ; dactyli of first 

 three pairs rather narrower than in A. spinimanus, but similarly sulcate 



