CLASS I. CRUSTACEA. 99 



scribed it in the eleventh vokmie of the Transactions of the Linneun 

 Socitty, p. 343. 



'■^Pahimoii, se7'ra^;« of Fabricius is distinct, and, if his description be 

 correct, it is not even referable to this genns ; he having expressly 

 given as its specific character ' Antenius posticls bijidis,' (hinder an- 

 tenna; bifid ;) whereas, in his generic character, he has stated these 

 organs to be trifid (' Antennre superiores trl/idcc.' '') 



Genus 36. ATIIANAS. Leach. 

 Four anterior legs didactyle : anterior pair larger than the second pair: 



exteriial double palpi with the last joint longer than the preceding 



joint. 

 Sp. 1. Ath. nitescens. Rostrum straight, and simple. 

 Cancer {Astucus) nitescens. Montagus MSS. Athanas nitescens. Leach, 



Trans. Linn. Soc. — Supp. to Encycl. P>ril. — j\]ul. Podoph. Brit. tab. 44. 

 Inhabits the southern coast of Devonshire. 



Stirps 5. — E.rternal antenna: inserted below the internal : interior ones 

 with a large scale at their base. Legs for movement sixteen. 



Genus 37. MYSIS. Latr., Leach. Praunus. L^each. 



Legs bifid, the last joint of the four anterior pairs with the interior 

 laciniu uniarticulate, ovate, compressed ; of the other pairs of legs 

 multiarticulate : external double palpi with the middle joint of the 

 internal footstalk longest, the first very short. 



At the base of the abdomen of the female is situated the external 

 uterus, composed of two valve-like membranes, in which the young 

 ones, just excluded from the egg, live and grow imtil they become 

 strong enough to take care of themselves. 



The animals of this genus swim with their head uppermost, and with 

 their eyes spreading, which gives them a singular and grotesque ap- 

 pearance. 



* hitcrmediatc lamella of the tail eniarginate. 



Sp. 1. ]\L/sis spinulosa. Tail with the intermediate lamella externally 

 spinulose; the apex acutely eniarginate ; exterior lamellce acuminate, 

 and very 'broadly ciliated. 



Praunus flexuosus. Leach, Edin. Encycl. vii. 401. INIysis spinulosa. 

 Leach, Trans. Linn. Soc. xi. 350. — Supp. to Enci/cl. Brit. i. 422. 



Inhabits the Frith of Forth near Leith. 



" Colour when alive, pellucid cinereous : eyes black, red at their 

 base : lamina: of the external antenna' with a l)lack longitudinal line 

 and spots. A clouded spot on each side of the hinder part of the 

 thorax, and anotlier above the legs. Every segment of the body 

 most beautifully marked with a reddish-rust coloured spot, disposed 

 in an arborescent form ; tail fin spotted with the same colour, mixed 

 with black : pouch of the female with two rows of fuscous-black 

 spots : under side of the abdomen regularly mottled with rufous black." 



