MONOGRAPH OF THE LEUCOSIADyE. 309 



Species unica, Nursilia dentata, milii (Tab. XXXIV. fig. 6). 

 Hab. in oceano Indico. Mus. Brit. 



Carapace rather broader than long, the margin laminated ; a slight fissure between the 

 hepatic and branchial regions, an obtusely triangular tooth on the margin of the former, 

 and three slight angular projections on the latter ; several small projecting teeth on the 

 surface of the carapace, and a longitudinal carina, on the posterior half of which are three 

 strong spines curved forwards ; an elevated line on the branchial region. External foot- 

 jaws extending forwards to the frontal margin, meeting only at the apex, and leaving an 

 interspace, the posterior part of which is filled by the last joint of the abdomen. The 

 anterior legs are long and slender, the hand tumid on the proximal portion ; the fingers 

 longer than the hand, very slender, curved at the extremity, and finely toothed. The 

 abdomen of the female extremely convex, the terminal joint somewhat triangular, and 

 extending forwards between the base of the foot-jaws. 



A single specimen, a female, is in the British Museum. 



Genus Arcania, Leach. 



Char. Gen. — Testa globulosa, spinis seu tuberculis elevatis plurimis armata. Orbita supra et extrorsiim 

 aperta. Fossa antennaria longitudinales. Pedipalpi externi caule exteriore recto, lineari, apice 

 interiore emarginato-truncato ; caule interiore gradatim acuminato. Pedes antici gracillimi. Abdomen 

 Maris lanceolatum, segmentis a tertio ad sextum vel ad quintum coalitis. 



This genus is closely allied to Iphis, from which it differs in the more globular form of 

 the body, in the number and character of the spines with which it is armed, and in the 

 form of the external foot-jaws. 



Arcania Erinaceus, Herbst. Corpore atque membris dense spinosis, spinis spinulosis. 



Cancer Erinaceus, Herbst, t. 20. f. 111. 



Leucosia Erinaceus, Fabr. Suppl. p. 352. 



Arcania Erinaceus, Leach, Zool. Miscell. iii. p. 24. Edw. Crust, ii. p. 134. 



Hab. in mari Indico. Muss. Brit., Soc. Linn., Bell. 



A well-known species, figured by Herbst and by several subsequent authors. It differs 

 from other species in the numerous spines with which it is armed, and in the spines being 

 themselves spinulose. 



Arcania undecim-spinosa, De Haan. "Thorace spinuloso, spinulis obtusis, ambitu 

 11-spinoso, spinis acutis simplicibus ; brachiis granulatis, digitis manibus longio- 

 ribus." 



De Haan, Crust. Japon. p. 135. t. 33. f. 8. 

 Hab. in Japonia. 



Arcania novem-spinosa, Adams and White. "Thorace lsevi, granuloso, marginibus 

 latero-anterioribus spinis duabus, latero-posterioribus spinis duabus, posteriore spina 

 longa recta." 



Iphis novem-spinosa, Adams and White, Crust, of the Voyage of the Samarang, p. 56. t. 13. f. 1. 



2 s2 



