CRAYFISHES. 393 
branchial formula is the same as in the genus Cheraps, and essentially the same 
as in Paranephrops; but according to Nobili the podobranchiae of the eighth 
and ninth somites are not furnished with an ala or lamina in the genus Astacone- 
phrops, whereas in the genus Cheraps these podobranchiae are alate. 
PARASTACUS ARAUCANIUS, Sp. Nov. 
Plate 4. 
Male:— Cephalothorax shorter than the abdomen, strongly compressed 
laterally, mostly smooth, minutely granulated on the sides; areola broad (about 
two thirds as broad as long), minutely punctated; rostrum short, not reaching 
the distal end of the second antennulary segment, margins elevated, slightly 
convergent from base to near the tip, where they abruptly converge to form the 
abbreviated acumen; the infero-lateral edges of the rostrum are visible from 
above, forming the superior border of the orbit separated from the supero-lateral 
edge of the rostrum by a groove; distal half of the rostrum concave above; 
antero-lateral margins of the carapace produced into a prominent, rounded 
angle below the small eye which lies in a deep and uncommonly complete orbit. 
Post-orbital ridges, obsolete. The pleural angles of the abdomen are rounded, 
the telson long with a pair of lateral spines and a longitudinal median furrow on 
its upper face along its distal half; the median rib on the upper side of the inner 
branch of the last pair of abdominal appendages ends in a small spine situate 
a little distance from the margin. Antennal scale short and broad. The 
chelipeds are asymmetrical, the right one being the larger; the meros is tuber- 
culated on its lower face, granulate on the superior margin, but destitute of 
spines; the surface of the carpus is lightly squamoso-granulate, the granulations 
becoming more pronounced on the supero-interior edge where they take the form 
of blunt tubercles; the chela, too, is lightly squamoso-granulate, without any 
prominent spine or tubercle, except one blunt tubercle or tooth near the base of 
the immovable finger; the superior and inferior borders are rounded. 
Dimensions. Length, 42 mm.; length of cephalothorax, 19 mm.; length 
of areola, 6 mm., breadth of areola, 4 mm.; length of larger claw, 15.5 mm., 
breadth of do., 7 mm., length of dactylus, 8.5 mm. 
Corral, Chile, Dec. 18, 1908, in a cascade stream. Thomas Barbour coll., 
Wily Gio Zen INOS Wei 
This species is related to P. nicoleti (Phil.) and P. hassleri Fax. Like these it 
has a strongly compressed cephalothorax, indicating a burrow-dwelling species. 
