432 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXXVI. 



redescribe and figure it. No general figure has ever been given, 

 although Kinahan gave detailed drawings of the uropod and the 

 terminal abdominal segment. It seems strange that, although this 



isopod is said to be numerous in Ja- 

 maica, no specimens exist, so far as I 

 know, in any museum except the British 

 Museum. 



Family ARM ADILLIDIDiE . 



ACANTHONISCUS Kinahan. 



AcantJwniscus Kinahan, Proc. Dublin 

 University, I, 1S59, p. 197. 



ACANTHONISCUS SPINIGER Kinahan. 



Acanthoniscus spiniger White (nomen 

 nudum), List Crust. Brit. Museum, 

 1847, p. 99. — Gosse, A Naturalist's 

 Sojourn in Jamaica, 1851, p. 65. — 

 Kinahan, Proc. Dublin University, I, 

 1859, p. 197, pi. 19, fig. 4.— Budde- 

 Lund, Crust. Isop. Terrestria, 1885, 

 pp. 241-242.— Richardson, Bull. U. S. 

 Nat. Mus., No. 54, 1905, pp. 637-638, 

 592 footnote. 



Body oblong ovate, capable of rolling 

 up into a ball. Color, in alcohol, dark 

 brown, with irregular spots of light brown. 



Head much wider than long, with the front emarginate and the 

 lateral angles acutely produced. The eyes are large, bulbous, com- 

 posite, and situated at the post-lateral 

 angles of the head. On the posterior mar- 

 gin of the head are three spines, one in 

 the median line and one on either side, 

 close to the eye, the median spine being 

 smaller than the other two. The first pair 

 of antenna) are rudimentary and incon- 

 spicuous. The second pair are broken and 

 the flagellum lost. The first article of the 

 peduncle is short; the second and third 

 are long and subequal; the fourth is one 

 and a half times longer than the third ; the 

 fifth is about one and a half times longer 

 than the fourth. 



The first segment of the thorax is longer 

 than any of those following. The lateral 

 parts are produced in large, rounded processes, which extend down- 

 ward and upward, surrounding the posterior portion of the head. 

 This segment is armed with two extremely long spines, one on either 



Fig. 1. — Acanthoniscus spiniger. 



Fig. 2. — Acanthoniscus spini- 

 gek. Second antenna. X 23. 

 (Flagellum lost.) 



