no. 1136. OBSERVATIONS ON THE ASTACIDJE— FAXON. 645 



not obliterated and the sides of the rostrum are less strongly conver- 

 gent. This is without doubt to be considered the typical form of 

 G. elarMi, since G-irard's specimens were collected in the same region, 

 somewhere between San Antonio and El Paso del Korte. 



CAMBARUS ACHERONTIS Lonnberg. 



(Plate LXII, figs. 1-5.) 



Cambarus acheronfis L5nnberg, Zoolog. Anz., XVII, pp. 125-127, 1894; Bihang 

 till K. Svenska Vet.-Akad. Handlingar, XX, Pt. 4, p. 6., figs. 1-6, 1894. 



Female. — Rostrum broad, excavated, superior lateral margins raised 

 into sharp carina? which overhang the inferior lateral margins and con- 

 tinue backward inside of and parallel with the postorbital ridges; a 

 pair of sharp projecting angles or teeth near the tip at base of the acu- 

 men; acumen short, acute. Rostrum, gastric region, and areola smooth 

 and polished; sides of carapace thickly studded with small papilla?, or 

 tubercles; postorbital ridges furnished with a small spine at the ante- 

 rior end; areola almost obliterated in the middle by the apposition of 

 the branchio cardiac lines ; posterior section of carapace equal in length 

 to the distance between the cervical groove and the anterior spines of 

 the postorbital ridges. 



Abdomen a little longer than the cephalo-thorax, smooth; telson 

 three or two spined on each side of tbe anterior segment, posterior 

 segment subtruncate. 



Antennae very long, much longer than the body; a small external 

 spine behind the base of the antennal scale; antennal scale very broad, 

 broadest at the middle, apical end rounded and armed with a small 

 external spine. Epistome short, broad, anterior border convex. 



Chelipeds slender; merus furnished with the customary biserial spines 

 below, superior margin spinulose, outer and inner faces sparsely granu- 

 lated; carpus with a longitudinal furrow above, tuberculiferous, the 

 tubercles tending to assume the form of short spines on the inner side; 

 chela? subcylindrical, granulated, the granules on the inner or upper 

 margin of the hand taking on the form of blunt spines; fingers long, 

 slender, inner and outer sides costate, upper margin of the dactylus 

 tuberculate, cutting edges of fingers irregularly denticulate on the 

 proximal half. 



Length 75 mm.; carapace 39 mm.; from tip of rostrum to cervical 

 groove 23.5 mm. ; from cervical groove to posterior border of carapace 

 16 mm. ; length of rostrum from tip to anterior spines of postorbital 

 ridges 9 mm.; width of rostrum 4.5 mm. 



Annulus ventralis transverse, with a prominent posterior tubercle 

 and a crescentic anterior fossa. 



In a young male of the second form, 43 mm. in length, the third pair 

 of legs are furnished with a blunt hook on the third segment, while 

 the corresponding segment of the fourth pair bears a small tubercle, 

 the vestige of the hook of the adult. The first abdominal appendages 



