CLASS I. CRUSTACEA. 
00 
Scribed it in the eleventh volume of the Transactions of the Linnean 
Society, p. 348. 
“Palamon serratus of Fabricius is distinct, and, if his description be 
correct, it is not even referable to this genus; he having expressly 
given as its specific character ‘Antemi is posticis bijidis,’ (hinder an- 
tennas bifid ;) whereas, in his generic character, he has stated these 
organs to be trifid (‘ Antenna superiores irifulte.' ’’) 
Genus 36. ATHANAS. Peach. 
Four anterior legs didactylc : anterior pair larger than the second pair: 
external double palpi with tire last joint longer than the preceding 
joint. 
®P- 1. Ath. nltescens. Rostrum straight, and simple. 
Cancer (Astacus) nitescens. Montagu's MSS. Athanas nitescens. Leach, 
Pl ans. Linn. Soc. — Sapp, to Encycl. Brit. — Mai. Podop/t. Brit. tab. 44. 
Inhabits the southern coast of Devonshire. 
Stirps 5. External antenna: inserted below the internal : interior ones 
■with a large scale at their base. Legs for movement sixteen. 
Genus 37. MY SIS. Lntr., Leach. Praunus. Leach. 
Pegs bifid, the last joint of the four anterior pairs with the interior 
lacinia unmrticulate, ovate, compressed ; of the other pairs of legs 
rnultiarticulate : 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 until 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. 
* Intermediate lamella of tlw tail emarginate. 
®P- 1. Mysis spinvlosu. Tail with tiie intermediate lamella externally 
spinulose; the apex acutely emarginate; exterior lamell® acuminate, 
and very broadly ciliated. 
^ r aunus ftexuosus. Leach , FA in. Encyd. vii. 401. Mysis spinulosa. 
Leach, Trans. Linn. Soc. xi. 350. — Supp. to Encyd. 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 black longitudinal line 
a nd spots. A clouded spot on each side of the hinder part ot the 
thorax, and another above the legs. Every segment ol the body 
most beautifully marked with a reddish-rust coloured spot, disposed 
in an arborescent form ; tail fin spotted with the same colour, mixed 
"nth black : pouch of the female with two rows of fuscous-black 
spots ; under side of the abdomen regularly mottled with rufous black.’' 
