233 



Sclerochiton thielei, n. sp. 



{ = Sclerochiton miles (Carpenter) of Thiele, Revis. des Syst. der Chitonen, Zool., 1910, 

 pp. 94, 95, pi. X., figs. 16-23.) 



The three specimens described and figured by Dr. Thiele (I.e.) were collected 

 at Pulotikus, Benkulen, in Sumatra, by Ed. V. Martens. Dr. Thiele remarks, 

 "This species is certainly closely related to Sclerochiton miles, from Torres 

 Straits, but whether it is really identical v/ith that species or not, cannot be 

 concluded with any certainty from the description." 



The rediscovery of Carpenter's (MS.) shell 6". miles, makes it quite clear 

 that although very similar in sculpture and form the characters of the girdle 

 show it to be quite distinct. 



Thiele says in reference to the Sumatra shells : — "The scales upon the 

 upperside of the girdle are of different sizes, sometimes even 05 mm. broad, 

 with converging ribs on their free ends. Between them and over the edge, there 

 are small calcareous needles, about 80 [i long and 12 fx thick, while the fringe 

 needles are about 150 /x long and 33 /u, thick." There are no spicules between 

 the girdle scales of Sclerochiton miles and no fringe spicules, showing that the 

 two are not conspecific ; the Sumatra shell conforms to Dr. Thiele's definition 

 of the genus Sclerochiton, whereas S. miles, owing to its lack of girdle spicules, 

 does not. 



I have therefore much pleasure in naming the species described (I.e.) after 

 Dr. Thiele, in recognition of the splendid work he has rendered in his production 

 of his "Revision des Systems der Chitonen." 



Family Ischnochitonidae; Pilsbry. 



Sub-Family Ischnochitoninae, Pilsbry. 



Genus Lophochiton, n. gen. 



Having strong radiating ribs or flutes on both end valves ; lateral areas, 

 two radial ribs ; median areas, coarsely sculptured with longitudinal ribs com- 

 posed of closely-packed granules. Numerous slits in both end valves and 1-1 ■ 

 in median, teeth sharp, slits broad and shallow, but in no case "festooned" 

 upwards at slits, as is the case in the genus CaUistochiton; slits in end valves 

 mostly opposite to the ribs, except the outer ones. A striking feature in the 

 type species, possibly of secondary importance, is the existence on the pleural 

 areas and on the posterior margin of all, except the tail valve, of long, finger- 

 shaped, often coalesced granules ; girdle clothed with thin, flattened, rather large, 

 imbricating, ribbed scales. 



Note. — The sculpture of the genus CaUistochiton is simulated in the sculpture 

 of the end valves, and lateral areas to a less degree, and also in the placing of 

 the slits mostly opposite the ribs in the end valves. On the other hand, it 

 corresponds with the Ischnochitoninae, in having sharp teeth in the insertion 

 plate, and the entire absence of "festooning" at the slits. I think it not unlikely 

 that Torr's highly-sculptured Ischnochiton bednalH may belong to this genus, 

 and possibly Ischnochiton pilsbryi, Bed., as well, but I have not examined dis- 

 articulated specimens of these. Dr. Thiele points out that the correspondence 

 of the slitting with the ribs is not constant in members of the genus CaUisto- 

 chiton, citing C. adenensis, Smith, as an example. I have examined specimens 

 of that species in my collection which were given to me by Major Dvipuis, and find 

 that this is correct, as regards the end valves, the festooning in them being also 

 suppressed; the slits in the median valves of that species are "festooned," as 

 in typical Callistochitons. 



