44 AMPHINEURA. [Polyplttcophorct. 



Genus 4. ACANTHOPLEURA, Guilding, 1835. 



Acanthopleura, Guilding, Zool. Journ., v, 1835. 28 (in part). Type : Chiton 

 spinosus, Brug. Corephium, Gray, P.Z.S.. 1847, 65, 68; not Brown. 

 1827. Maiigeria. Gray, Guide Brit. Mus., 1857, 183 (in part). Fran, 

 cisia. Carpenter, in Ball, Proc. U.S. Nat. Mus., 1881, 284, 289. 290 (1882). 



Valves exposed, beaked, generally lustreless or eroded ; provided 

 with eyes on the forward part of the latreal areas and the end valves ; 

 mucro posterior ; interior coloured, the tegmentum broadly inflexed at 

 the posterior margin of each valve. Insertion plates all conspicuously 

 pectinated outside and directed forward. Girdle thick, covered with 

 small or large calcareous spines. (Pilsbry.) 



A widely spread genus, being recorded from the West Indies, Strait 

 of Magellan, west coast of South America, Galapagos, Tonga, Fiji, 

 New Caledonia, north Australia, New Guinea, Java, Philippine Islands, 

 Bismarck Archipelago, Mauritius, Reunion, Comoro Islands, Zanzibar, 

 Cape of Good Hope, Cape Verde Islands, &c. 



Subgen. 1. MAUGERIA, Gray, 1857. 



Maugeria, Gray, Guide Syst. Dist. Moll. Brit. Mus., 183 (in part). Type : 

 Ch. granulatus, Gmel. Acanthopleura, Carpenter, Table Reg. Chitons, 

 1873 ; not Guilding. q.v. 



Exterior lustreless ; tail valve having numerous (7-12) slits in the 

 short crenulated insertion plate, median valves 1 slit, the exposed 

 coating or tegmentum wider than the articulamentum, or inner layer ; 

 sinus not toothed, the sutural plates connected across it ; girdle thick, 

 densely beset with calcareous spinelets. (Pilsbry.) 



1. Acanthopleura granulata, Gmelin, 1790. Plate 2, fig. 21 ; Plate 5, 

 fig. 2. 



Chiton granulatus, Gmel., Syst. Nat., ed. xiii, 3205. Acanthopleura granu- 

 lata, Gmel., Man. Conch' (1), xiv, 227. pi. 50; .1. Mai., xii. 70. Chiton 

 'magellaniciis, Gmel. C. piceus, Gmel. C. occidentalis. Reeve. C. sala- 

 mander. Spengler. C. tuberculatus, L. : Sohvoter, not Linnseus. C. itn- 

 guiculatus et convexus, Blainville. C. blauneri et mucronulatus. Shuttle- 

 worth. Tonicia corticata, Hutton, T.N.Z.I.. iv, 180. 



Shell oblong, moderately elevated or roundly arched, almost 

 always eroded, cinereous, girdle with calcareous spinelets. Anterior 

 valve closely granulated, the granules diminishing in size toward the 

 apex ; interspaces with numerous small black eyes. Intermediate 

 valves beaked, roundly arched, the jugum of the first median valve 

 granulate, on the succeeding valves minutely wrinkled ; lateral areas 

 having the granules disposed in longitudinal rows in front of the lateral 

 areas, which are but slightly raised, granose, and interspersed with 

 numerous eyes. Posterior valve with a few growth - ridges, closely 

 granulated, eyes less numerous ; rnucro swollen, posterior. Girdle 

 thick and fleshy, densely covered with short unequal spinelets, which 



