308 Dr. LzaAcn's Arrangement of the Crustacea, ác. 
and although from the infant state of our knowledge I cannot 
. venture to propose named divisions, yet I shall endeavour to dis- 
pose the genera into what appear to be natural groups. 
A. Aldomen maris 5-articulatum articulo medio longiore, femine 
7-articulatum. Pedes 2 antici didactyli. 
Divisio I. Testa subrhomboidalis. Pedes duo antici longissimi, di- 
gitis deflexis. 
Genera. 
1, LAMBRUS. 
Divisio II. Testa postice truncata. Pedes duo antici maris elon- | 
ti, fæminæ mediocres. 
à 3 
Subdivisio 1. Antenne elongate utrinque ciliate. 
Testa elongato-ovata. Pedipalpi gemini externi articulo secundo 
longiore. 
Testa subcircularis ; orbita integra. Ungues acuti, flexuosi. Pedi- 
palpi gemini externi caulis interni articulo secundo breviore. 
Testa subcircularis; orbita fissuris 2. Ungues recti. 'Pedipalpi 
gemini externi caulis interni articulo secundo longiore. 
Subdivisio 2. Antenne mediocres simplices. Pedes postici unguibus 
compressis, natatoriis. 
Orbita integra. Ungues omnes compressi. 
Orbita superne fissura 1, Ungues postici subeompressi, acuti. 
Orbita superne fissuris 2. Ungues postici valde compressi. Pedes 
2 antici inzquales. : 
Orbita superne fissuris 2, Ungues postici valde compressi. Pedes 
2 antici equales. 
Subdivisio 3. Antenne mediocres simplices. Pedes 8 postici natatorii. 
Subdivisio 4. Antenne simplices, breves. Pedes 8 postici consimiles, 
simplices. 
Pedes 2 antici simplices, inequales. — Antenne externae iuter oculo- 
rum canthum et frontem inserte. 
Pedes 2 antici simplices, inequales. Antenne in ovalar cantho 
interno insertæ, 
Pedes 2 antici cristati, equales. 
B. Abdomen in utroque sexu 7-arliculatum, Pedes duo antici di- 
dactyli. 
2. CoRYsTEs. 
3. THIA. 
4, ÄTELECYCLUS, 
5. PoRTUMNUS. 
6. CARCINUS, 
7. PonTUNUS. 
8. LUPA. 
9. MATUTA. 
10. CANCER, 
11, XANTHO. 
12. CALAPPA. 
Divisio 
