S4 MODERN SYSTrM. 



h. Interior antenna uith moderate footstalks. 



Fam. IV. AsTACiD.i. IxaeWs MSS. 

 Aiitenna: inserted in the same horizontal hne, interior ones with two 



setffi, the exterior ones simple : legs for walking ten, anterior pair of 



these largest. 

 Stirps 1. — Exterior lamella of the tail composed of one part. 



Genus 23. GEBIA. Leach. 



Two anterior legs equal, subdidactyle, witli the thimil) short : interior an- 

 tenna: with an elongate peduncle; the second joint shortest, the third 

 largest and cylindric : external double palpi with the third joint of the 

 internal footstalk shortest : tail with 1 )road lamelkf ; the exterior 

 ones costated, the middle one quadrate. 



Sp. 1. Geb. Deltdura. Abdomen with the hack membranaceous : tail with 

 the apex of the exterior lamella dilated and somewhat rounded ; in- 

 terior one truncate, and formed like the Cheek delta. 



Gebia deltaura. Lcac/t, Trans. Linn. Soc. xi, '^V2.—Mul. Podoph. Brit, 

 tub. 31. Jig. 9, 10. 



Inhabits beneath the sand on the southern coast of Devonshire, and is 

 found by digging to the depth of two or three feet. 



Genus 24. CALLIANASSA. Leach. 



Four anterior legs didactyle ; anterior pair largest, very unequal ; second 

 pair less; third pair monodactyle ; fourth and fifth pairs spurious : 

 internal antennae with an elongate biarticulate peduncle, the second 

 joint longest : external doable palpi with the second joint of the inter- 

 nal footstalk largest and compressed: tail with broad lamella;; the 

 middle process elongate-triangular, with the apex rounded. 



The thorax anteriorly abruptly subacuminate; the rostriform pro- 

 cess divided from the shell by a suture: anterior pair of legs very 

 much compressed, the liand articulated : the larger leg with the base 

 of its wrist furnished with a curved process. 



Sp. 1. Cal. subtcrranca. Shell with the rostriform i)roceM_, with one Ion- 

 gitudinal ridge, the point rounded. 



Cancer Astacus subterraneus. Montagti, Trans. Linn. Soc. xi. Callianassa 

 subterranea. Leach, Edin. Encijcl. vii. 100. — Trans. Linn. Soc. xi. oVo. 

 —Supp. to Encycl. Brit. i. VlO.—Mulac. Bodoph. Brit. tab. 32. 



This animal lives beneath the sand on the sea-shore. It was first 

 described by INlontagu, who found it l)y digging in a sand-bank in 

 the estuary of Kingsbridge, on the soutliern coast of Devon. 

 Genus 25. AXIUS. Leach. 



Four anterior legs didactyle; anterior pair largest, and somewhat un- 

 equal; third, fourth, and fifth pairs iurnished with a compressetl 

 claw: k<mV»r fl?/if)i/uc with a three-jointed peduncle, the first joint 

 longest : external double palpi with the two first joints somewhat large 



