Kingsley.] 146 [March 5, 
proximal portion above, distally with a laminiform crest; carpus ex- 
ternally tuberculate; hand compressed, fingers widely gaping, distally 
toothed, pollex bent downwards and then upwards, dactylus regularly 
curved, with a tooth on the occludent margin near the base. 
Remaining feet slender, cylindrical, decreasing in length backward; 
meros and carpus of the first pair of ambulatory feet, each with a 
long, slender, acute spine above, near the distal extremities; pro- 
podal joints of all the feet with a rounded laminiform process for the 
articulation of the dactyli; dactyli strongly curved, pectino-denticu- 
late beneath. 
One male in the Museum of the Peabody Academy of Science 
from Lower California gives the following measurements. 
Length of carapax, 17.5 mm.; breadth, 13.5 mm.; ratio, 1: 0.72. 
This species differs from MZ. aculeatus as shown in Bell’s descrip- 
tion and figure (Trans. Zool. Soc., London, 11, 50, pl. rx, f. 7.) in 
having many tubercles on the cardiac region, and only two spines on 
each branchial region (J. aculeatus has four), in wanting the spines on - 
the meros of third pair of feet, and from both MV. aculeatus and M. bi- 
cornutus in having the horns of the rostrum straight and not incurved. 
Genus ANAPTYCHUS Stm. (ALA Lockington). 
Anaptychus cornutus Stm. 
Anaptychus cornutus Stimpson, Annals N. Y. Lyceum, vu, 184, pl. 
11, f. 1, (1859); Streets and Kingsley, J. c., 1x, 105, (1877). Ala 
spinosa Lockington, Proceedings of the California Academy of 
Science, vil, 66, (1877, extras issued in 1876). 
In addition to the characters given by Stimpson, the following may 
be observed in the specimen sent by Mr. Lockington from the Gulf 
of California as the type of his Ala spinosa. The median portion 
of the posterior crest six lobed; there are nine depressed tubercles 
on the gastric region, and in our specimen the first tooth of the 
antero-lateral margin is narrower and more slender than it is repre- 
sented in Stimpson’s figure. | 
Length of carapax, 19 mm.; greatest breadth, 24 mm.; ratio, 
1: 1.24. 
Sub-Family MITHRACINAE. 
Genus MitHRACULUS White. 
Mithraculus areolatus Streets and Kingsley. 
Mithrax areolatus Lockington, J. c. vii, 71, (1876). Mithraculus 
areolatus Streets and Kingsley, 1. c. 1x, 104, (1817). 
