OF ARTS AND SCIENCES. Ill 



of basal se";ment of the telson. Terminal seirment of telson shorter 

 than basal part, one third broader than long, hind margin concave. 

 Anterior process of epistoma subquadrangular. Basal segment of 

 antennules with a sharp spine below near the inner margin, half-way 

 towards the end of the segment. Antennae shorter than the body, 

 second and third segments with an external sharp tooth. Antennal 

 scale equal to peduncle, slightly surpassing the rostrum, broad, broad- 

 est at the middle, rounded at apex, terminating in a short spine, ex- 

 ternal margin inflated. Third maxillipeds hairy within and below. 

 Clielipeds slender, chela long, subcylindrical, squaraoso-tuberculate, 

 tubercles ciliate anteriorly, internal border straight, serrate. Fingers 

 as long as the hand, with alternate longitudinal ribs and lines of cili- 

 ate impressed dots. Opposed margins of fingers straight, unidentate. 

 Carpus squamoso-tuberculate within, obsoletely so without, with one 

 prominent spine on inner border. Meros punctate outside, ciliato- 

 tuberculate within and on upper margin, which has two ante-apical 

 spines obliquely placed ; two rows of spines beneath. Third and fourth 

 pairs of legs hooked on third segments, hooks of fourth pair bitubercu- 

 late. Fifth pair of legs with a flattened laminate tubercle on basal 

 joint. Anterior abdominal appendages of moderate length, bifid at 

 apex, outer part forming a broad flattened plate whose anterior margin 

 is furnished with hairs and one strong seta, the posterior margin of 

 the plate produced anteriorly into a blunt tooth-like process. Inner 

 part bearded within, and produced into a long erect spine, which much 

 exceeds in length the outer part of the appendage. 



Length, 62 mm. Rostrum, 6 mm. Carapace, 30 mm. From tip 

 of rostrum to cervical groove, 19.5 mm. From cervical groove to 

 posterior border of carapace, 10. .5 mm. Abdomen, 32 mm. Width 

 of areola, 7 mm. Antennie, 47 mm. Chelipeds, 49 mm. Chela, 

 23 mm. "Width of chela, 6 mm. 



St. John's River, Hawkinsville, Orange Co., Fla. : J. A. Allen. 



A well-marked species with toothless excavated rostrum (younger 

 specimens probably have marginal rostral teeth), narrow areola, long, 

 subcylindrical chelipeds covered with ciliated squamous tubercles. The 

 first abdominal legs are not jointed, the hooks on the third and fourth 

 pairs of thoracic legs are large and well-finished, so that I consider 

 the single specimen examined to be the first form. 



In the collection of the Academy of Natural Sciences of Philadel- 

 phia there is a specimen from Hernando Co., Fla., Jos. W. Wilcox, 

 which is probably the second form of the male of this species. Tlie 

 sexual appendages are not articulated at the base. The hooks on the 



