THE CANCROID CRABS OF AMERICA 



337 



FORMA SIMPSONI " new 



Plate 157, Figures 1 and 2 



Type Locality. — Apalachicola, Fla. Type, female, Cat. No. 56382, 

 U.S.N.M. 



Carapace rather narrow, more hexagonal than other forms of the 

 species, due to the advanced front, the second lateral tooth being 

 similar to, and no larger than the first tooth and situated almost 

 entirely behind the level of the first tooth, the chord of the antero- 

 lateral margin short, the last three teeth rather small, pointed, well 

 separated, third pointing forward or in the old obliquely forward and 

 outward, fifth tooth oblique, directed more outward in the old; a 

 carina follows its summit and is continued on the carapace. Surface 

 with many raised granulated lines, and with a scattering of stout 

 vesiculous hau-s ; these hairs form also a dense covering on the ventral 

 surface of the branchial region, the outer surface of the ischium of the 

 cheliped and outline the segments of sternum and abdomen. Sub- 

 hepatic tubercle flattened, free end directed forward. Chelipeds very 

 unequal- in both sexes, the major palm as high as its middle length. 

 Legs of first three pairs narrow and rather long, in the fourth pair the 

 last three articles are short and broad. 



The forms here recognized are not always easily separated from one 

 another. Some specimens can not be referred to any one of them 

 but are intermediate. Intermediates may be found also in the same 

 gathering with others representing a true form.^^ 



Measurements 



Forma 



Front 

 width 



typica 



obesa 



crassa 



simpsoni 



12. 1 

 15 

 16 

 10.2 



Habitat. — Both forma typica and forma obesa were found in large 

 numbers on the South Carolina coast by a survey party on the steamer 

 Fish Hawk in 1891. Forma typica was taken at low tide on bunches 

 of oysters while forma obesa was living in burrows in the banks 

 above the water line. The shape of the convex form is attributable 

 to its habitat, the mode of life being calculated to mold the body into 

 a subcylindrical shape and to eliminate sharp points. Joseph D. 

 Mitchell says oi forma simpsoni on the coast of Texas, "It lives on 

 oyster reefs and does not dig holes but scoops a place under a large 



<• For Charles T. Simpson, of Little River, Fla., who has devoted many years to the development of the 

 flora and fauna of the State. 



*' Specimens of the different forms were sent to M. Gravier, Museum National d'Histoire Naturelle, 

 Paris, who compared them critically with type specimens of P. herbstii and P. crassus. 



79856—30 23 



