450 PHOr. p. MAETIN DUNCAN ON THE 



inclined to refer to the subgenus Pleurechinus, Agass. ; they 

 are unfortunately not large enough to comjDare directly with the 

 typical PleurecMnus hothryoides. They show clearly, however, 

 that we may expect to find in the China Seas a species of Temno- 

 pleurus still retaining the principal features so characteristic of 

 some of the Nummulitic species of India figured by D'Archiac 

 and Haiine (see pi. xiii. fig. 7, of Temnopleurus Valenciennesi of 

 their work), to which the specimens of the 'Challenger' are 

 most closely allied. 



" The outline of the test even in these young specimens (mea- 

 suring, the largest not more than 18 mm. in diameter) is high, 

 resembling already somewhat the globular shape of such species 

 of Amhlypneustes as A. griseus, and diff"ering from the other 

 species of Temnopleuridae, in which the outline of the test is 

 quite conical at a corresponding age. The genital ring is narrow, 

 compact, slightly pentagonal ; the genital plates are of uniform 

 size, with the exception of the madreporic genital, which is some- 

 what larger and rectangular in outline, the pores covering its 

 entire surface with the exception of the space occupied by tlie 

 ring of secondary tubercles, which runs along the inner edge of 

 the genital plates, separating them from the anal system. In 

 addition to this edging, the genital plates carry from two to three 

 tubercles, irregularly pla.ced on the plates, and a few miliaries. 

 The genital openings are deep, crescent-shaped notches, cut out 

 of the outer edge of the plates ; the genital plates are united along 

 the anal edge, and a distinct pit in the angle of the sutures 

 between the genital and oscular plates separates the latter from 

 the edge of the anal system. The anal system is covered by an 

 outer row of large triangular plates, with smaller elongate plates 

 arranged round the anal opening. 



" In the interambulacral area there are two disconnected pits at 

 the two extremities of the horizontal sutures separating the coronal 

 plates. The coronal plates carry from one to three large primary 

 tubercles, arranged in a horizontal row near the lower edge of 

 the plate, with a somewhat undulating horizontal line of smaller 

 secondary tubercles above that, the rest of the plate being filled 

 with granules, miliaries, and secondaries irregularly arranged. In 

 the ambulacral area the pits are only slightly smaller, but there 

 is only a single large pit at the median end of the suture ; the 

 pit at the other extremity of the suture is reduced to a minute 

 impression at the angle of the coronal plate adjoining the pori- 



