On a new Genus and Species of Land-Crahs. 187 



ance than the older one, the brighter ochraceous spots being- 

 much larger and more numerous. 



EXPLANATION OF PLATE XVI. 



Fi(/, 1. Zephronia excavata, profile ; 1 a, curled up. 



Fig. 2. SphcBrotlierium polituyn, profile ; 2 a, head, nuchal plate, and first 



foiu- dorsal segments, from above ; 2 b, head, nuchal plate, and 



first segment, from below ; 2 c, last two dorsal segments, from 



behind. 

 Fig. 3. Sphcerotheriiim maculatum, adult specimen, profile ; 3 a, young 



specimen, curled up ; 3 6, head, nuchal plate, and first segment, 



viewed in front. 

 Fig. A. Zeph-onia Icevissima, profile; 4 «, head, nuchal plate, and first 



three dorsal segments, from above ; 4 b, last two dorsal segments, 



from behind. 



XXYII. — On a new Genus and Species (Hyleeocarciuus 

 Humei) of Land-Orahs from the Nicohar Islands. By 

 James Wood-Mason, of Queen's College, Oxford *. 



Milne-Edwards, in his classical work on the entire class 

 of Crustacea, published in 1837, divides f the four then re- 

 cognized genera of the small but remarkable group of Gecar- 

 cinidae, or land-crabs properly so-called, into two divisions, 

 according as they have the terminal joints of the external 

 maxillipeds completely exposed or inserted on the internal 

 face of the third joint near its summit and completely hidden 

 beneath it ; and Dana in his great work not only adopts 

 these divisions, but gives them subfamily names \. " The 

 Gecarcinidse," he says, " pertain natm-ally to two groups or 

 subfamilies, one having the termination of the outer maxil- 

 lipeds exposed as usual, the other having this part concealed 

 beneath the second and third segments." The subfamilies 

 and genera are as follows : — 



Subfam. I. UCAIN^. Articulus maxillipedis externi quartus 

 apertus. 



1. Maxillipedes externi non Mantes. 



Gen. 1. UcA, Leach, Articulus maxillipedis externi quartus angulo 



externo insitus. 

 Gen. 2. Gecaecinuctts, M. -Edwards. Articulus maxillipedis externi 



quartus marginis medio apicalis tertii insitus. 



* Communicated by the Author. From the ' Journal of the Asiatic 

 Society of Bengal,' vol. xlii. part 2, 1873, having been read before the 

 Society August Gth, 1873. The original is accompanied bv two plates. 



t Hist. Nat. des Crust, vol. ii. p. 20. 



X United States Expl. Exped., Crust, vol. i. pp. 374, 375. 



13* 



