S4 MODERN SYSTEM. 



b. hilcrior antenna with moderute footstalks. 



Faiii. IV. AsTACiu.^E. Lcac/i's ]\ISS. 

 Antenmr inserted in the same horizontal line, interior ones with Iavo 

 seta% the exterior ones simple : legs for walking ten, anterior ])air of 

 these largest. 



Stirps 1. — Exterior lamdUi oi' the tail composed of one part. 



Genus !L>8. GEBIA. Leach. 



Tzco anterior legs equal, siibdidactyle, with the thumb short : interior an- 

 tcmuc with an elongate peduncle; the second joint shortest, the third 

 largest and cyHndric : external double palpi with the third joint o\' the 

 internal footstalk shortest : tail with broad lamella? ; the exterior 

 ones costated, the middle one quadrate. 



Sp. 1. Geb. Delldura. Abdomen willi the back membranaceous : tail u iih 

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

 terior one truncate, and formed like the Greek delta. 



Gebia dellaura. Ixaeli, Trans. Linn. Hoe. xi. 342. — Mul. Fodop/u Brit, 

 tab. 31. Jig. 9, 10. 



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

 found by digging to tiie deiUh of two or three feet. 



Genus 21. CALLIANASSA. Leach. 



Four anterior legs didactyle ; anterior pair largest, very une{(ual ; second 

 pair less; third ])air monodactyle ; fourth and fifth pairs spurious : 

 Juternal anlcmuL' witli an elongate biarficulate peduncle, the second 

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

 nal footstalk largest and conq>ressed: tail with broad lamella^; the 

 middle process elongate-triangular, with the apex rounded. 



The thorax anteriorly abru[)tly subacuminate ; the rostriform pro- 

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

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

 of its wrist furnished with a curved process. 



Sp. 1. Cal. sublciTanea. Shell with the rostriform process with one lon- 

 gitudinal ridge, the point rounded. 



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

 subterranea. Leach, Edin. Encj/cl. vii. 100. — Trans. Linn. Soc. xi. 343. 

 — Supp. to Encijcl. Brit. i. 420. — Maluc. Fodoph. Brit. tab. 32. 



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

 described by Montagu, who foimd it by digging in a sand-bank in 

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



Genus 25. AXIUS. Leach. 

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

 equal; third, fourth, and fifth pairs furnished with a compressed 

 claw: interior antcnntc with J. threc-ynnted ]icdunclc, the first joint 

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



