ASTACID.E. 41 



long) ; the foinalo is sinallor. The first abdominal leg of the male, 

 figured by me after the type, shows exactly the shape of tlie male 

 full-grown Forma 11., but not as well finished as it is always found 

 in the young specimens. I have not seen a similar young specimen 

 from New Orleans ; the snuillest is 2.6 unc. long, )jut agrees very well. 

 The 3'oung of C iiw/hHh/fvs, of which I have seen specimens 0.6 unc. 

 long, are very similar; but C. C/wyM' differs in having the rostrum exactly 

 triangular and a little attenuated at the tip (it is more dilated, with the 

 margins curved, in C. ini</lu(h/tcH) ; the acumen is longer, wore acute 

 (in C. Clarkii iy^Q ^s^ unc. left side, 3^ right side) ; the basis of the ros- 

 trum has two obsolete elevations connected in an obtuse angle ; the 

 lamina of the antennas is more elongated, smaller at the tip. 



In the Museum of the Natural Histoiy Society of Boston are two 

 females, together with a great number of apparently very young ani- 

 mals, before described by me. 



Cat. No. 1162, New Orleans, La., L. Agassiz. Mas. Form I. and II. 

 Fem. Spec. 12.* 



Cat. No. 166, New Orleans, La., L. Agassiz. Mas. Form I. Fem. Spec. 5. 



Cat. No. 264, New Orleans, La., Mr. Allen. Mas. Fem., young. Spec. 3. 



Cat. No. 1822, Mobile, Ala., L. Agassiz. Mas. Form II., young. Spec. 2. 



3. Cambarus troglodytes LeCoide. 



Astaciis troglodytes LeC, Proc. Acad. Philad., T. 7, p. 400. 



Figures on PI. I. and III. 

 First abdominal legs of the male : 



first form, fig. 1 1 in front, fig. 1 2 outside. 



second form, fig. 13 in front, fig. 14 outside. 

 Antennal lamina, fig. 141, o; epistoma, h; spine of the second joint of the exterior antenna, c. 



Mas. Rostro triangulari, lato, tertia parte longiori, suljdeflexo, ante 

 apicem acutum, brevem, paulo barbatum, utrinque leviter sinuato ; supra 

 fere piano Itevi, utrinque subtiliter marginato, tuberculo obsoleto piano 

 in foveola basali orbiculari ; cretis basalibus extus sulcatis, apice 

 subacutis, suliparallelis. Antennis gracililjus, corpore paulo breviori- 

 bus, articulis duobus basalibus dente externo parvo subacute ; antennis 

 internis articulo basali dente infero medio acuto; lamina externa 

 rostro longiori, articulo antennarura tertio vix breviori, lata, apice vix 

 rotundata, margine externo inflate, apice brevi spinoso. Epistomate 

 lato, antice et utrinque subsinuato (forma variabili, semper brevi, 

 lateriljus obliquis). Pedibus maxillaribus iiitus et basi sul^tus villosis. 

 Thorace postice latiori, postice subdepresso, granuloso, cephalothorace 

 medio fortius punctato, postice obsolete bicalloso, linea modice pro- 

 funda et sinuata, lateribus fissa, spina infera ad antennarum basi apicali 

 acuta ; areola media angusta, suljcarinata, postice latiori, transverse 



6 



