CLASS r. CRUSTACEA. 103 



Genus 5. LEUCOTIIOE. Leach. 

 Anterior pair of legs didactyle; the thumb biarticulatc: second pair with 



a dilated and compressed hand, furnis.hcd with a crooked thumb. 

 Sp. 1. Leu. arficulom. 

 Cancer articulasus. Mmitagii, Trans. Linn.Soc. vii. 71. f. G.f. 6. I^u- 



cothbe articulosa. Leach, Edin. EncycLVii. 403. — Trans'. Linn. Soc. 



xi. 35S. — Supp. to Encijcl. Brit. i. 42.5. 

 Inhabits the British sea, but is very rare. 



Stirps 3. — .J/i^fWHtf four-jointed, the last segment composed of several 

 little joints; upper ones longest. 



Subdivision 1. — Four anterior /eg.< vwnodactylc, second pair with a much 



dilated compressed hand. 



Genus 6. MRLITA. Leach. 



Anterior pair of legs monodactylc; second pair with the thumb inflexed 



on the palm: /«/7on each side with an elongate foliaccous lamella. 



Sp. 1. Mel. palniutu. Body blackish: antciuue and legs annulated with 



pale colour. 

 Cancer palmatus. Montagu, Trans. Linn. S(k\ vii. 69. ISIelita palma- 

 ta. Leach, Edin. Enci/cl. vii. 403. — Trans. Linn. Soc. xi. 3j8. — Sajip. to 

 Enci/cl. Brit. i. 423. pi. 21. 

 Inhabits the sea shore on the Devonshire coast under stones. 



Genus 7. INI.ERA. Lxach. 

 Four anterior l,gs didactyle ; thumb of the second pair bent on the side 



of the hand : tail with no foliaceous appendices. 

 Sp. 1. Ma. grossinuina. 



Cancer Gammurus grossimanus. Montagu, Trans. Linn. Soc. ix. 97. t. 4, 

 f. 5. Ma;ra grossimana. l.cach, Edin. Encycl. vii. 403. — Trans. Linn, 

 Soc. xi. 359. — Snpp. to Encycl. Brit. i. 425. 

 Inhabits the southern coast of Devonshire beneath stones. 



Subdivision 2. — Tco anterior pair of legs monodaclyle and alike. 

 Genus 8. GAMMARUS. Latr., Leach. 

 Superior antennas furnished at the base of the fourth joint with a little 

 jointed seta: tail above with bundles of spines. 



* Tail with the superior double styles, having the upper style process 

 very short. 

 Sp. 1. Gam. agnaticus. Process between the antennje rounded, obtuse. 

 Gammarus Pulex. I^ach,Edin. Encycl. \n.iOQ— 432. Gammarus aqua- 

 ticus. Leach, Trans. Linn.Soc. xi. 359. — Snpp. to EnCycl. Brit.i. 425. 

 Inhabits ponds, ditches, and springs in great plenty. 

 Sp. 2. Gam. marinus. Process between the antenna^ subacuminate. 

 Gammarus marinus. Leach, Trans. i/««. 5oc. xi. 359. — Supp. to Encycl, 



Brit. i. 425, 

 Inhabits the sea on the southern coast of Devonshire in plenty. 



