CLASS r. CRUSTACEA. 
87 
stalk, one-jointed : anterior pair of legs unequal : eyes thick : shell 
ovate-orbicular, orbiculate-quadrate, or transverse subquadrate. 
All the species of this most interesting genus inhabit the bivalve 
shells of the acephalous Molluscu , and were supposed by the ancients 
to be consentaneous inmates with the animal, bound by mutual in- 
terest. 
Aristotle supposed them to act as sentinels, and believed that they 
guarded the Pinna (die animal in whose shell they were first observ- 
ed) front die attacks of its enemies, llondeletius and some other 
naturalists held die same opinion. 
hp- 1. Pin. Crouch'd. Shell orbieulate-subquadrate, soft, very smooth, with 
the sides dilated behind : front straight, obscurely subemarginate : 
hands oblong below, and the thighs above with a ciliated line : 
thumb subarcuate: abdomen very broad; the sides of the segment 
arcuate; die second and following ones distinctly notched; the fifth 
segment somewhat broader; the last narrower than the preceding 
segment. Fenuile. 
'Unoteres Cranchii. Leach, Malacost. Podoph. Brit. tali. 14. fig. 4. 5. 
The male of this species, which was discovered by Mr. J. Cranch, 
w hose name ithears, is unknown. It is distinguished from P ■ Pisum 
(the common species) by the form of the front of the shell, which is 
straight, and slightly notched; by the dilated hinder part of the shell, 
and by the abdomen, all the joints of which, excepting the first, are 
distinctly notched behind. 
s * Shell quadrate. Eyes with, a long peduncle. 
Genus 10. GONOPLAX. Leach. Ocypoda. Bose. 
Eyes terminating their peduncle: anterior pair of lees equal ; of the 
male very long ; of the female twice the length of the body : antenna 
half the length of the body, inserted at the internal canthus ot the 
eyes. 
The animals of this genus inhabit the ocean, preferring such parts 
as have a slimy bottom. They burrow laterally in the clay or slime, 
faking two entrances to their hole; entering by one and going out 
by the other. 
P- h Gon. hispinosa. Shell on each side with two spines: arms above, 
and wrists internally, with one spine, 
vancer angulatus. Penn. Brit. Zool. iv. t.5.f. 10. Fabr. Suppl. Entom. 
34 i. Ocypoda angulata. Bose, Hist. Nat. des Crust. 1. 198. 
Gonoplaxbispinosa. Leach, Trans. Linn. Soc.x i. 323 .— -E*!. Encycl. 
r 7~Supp. to Encycl. Bril. — Mai. Podoph. Brit. tab. 13. 
■hihabits the British sea. It is not uncommon at Salcombe and in 
Plymouth sound; and likewise occurs at Weymouth, and at Red 
Wharf in Anglesea. 
