56 THE TERTIARY FOSSIL ECHINOIDEA 



The shape of the test is rarely preserved except in young forms ; it is moderately 

 swollen, flattish, and ingoing actinally, and more or less turban-shaped above. (See 

 notice of the shape in the description of the l^attywar Echinoidea.) 



It is clear that the tubercles are imperforate and non-crenulate. In about forty 

 specimens we found one with two crenulate tubercles. The fossettes do not resemble 

 the true pits of Temnopleurus, Pleur echinus, Salmacis, &c.* 



On examining the specimens, descriptions, and drawings of the species of Bicfyo- 

 pleurus from the Ranikot series of Sind f, the resemblance to those now under con- 

 sideration is seen to be great. Yet these Miocene forms depart from the type, and even 

 ti-om that of J)ictyoj)leurus Eaimei, nobis %. The obliquity of the axis of the anal 

 opening exists in some forms it is true, but in most the opening is circular and there 

 is no obliquity. The tubercles are non-crenulate and imperforate in the Miocene forms, 

 and this and the evidently ornamental character of the fossettes recall Temnechinus of 

 Forbes. Admitting the alliance of these Miocene species with the genus Bictyopleurus, 

 are they separable from Temnechinus 1 The structure of the ambulacra and fossettes 

 in all is that of Temnechinus ; and the only difference in the ambulacra is that, instead 

 of there being one large tubercle with a vertical prolongation of the plate close to it 

 actinally, which separates the two fossettes of each plate, as in Temnechinus, the Kachh 

 forms have three tubercles and corresponding fossettes. But as these fossettes are 

 mere matters of ornamentation, the importance of considering the species as belonging 

 to Temnechinus is enhanced. It is curious that in their great work MM. d'Archiac 

 and Haime should have misrepresented Forbes, and endeavoured to render his 

 genus of no great value. Indeed they absorb the four species of the Crag (Temnechini) 

 into the genus Temnopleurus (op. cit. p. 202), and make a great mistake regarding the 

 geographical distribution. They state : — " La distribution geographique des especes 

 fossiles du genre Temnopleurus merite d'etre remarquee, puisque sur les neuf qui sont 

 connues, quatre appartiennent au Crag d'Angleterre, et cinq aux depots nummulitiques 

 de la Chaine d'Hala, sans que jusqu'a present on en ait trouve aucune autre ailleurs.^' 

 The species described by MM, d'Archiac and Haime did not come from the Num- 

 mulitic of India, but from the Miocene. No true Temnopleurid is found therein. 

 Justice and the rules of classification demand that the distinction which Forbes made 

 between Temnechinus and Temnopleurus should hold good ('-' Echinoderms of the Crag," 

 Pal. Soc. 1852, p. 5). The attempt on the part of MM. d'Archiac and 'Haime to absorb 

 Temnechinus fails in the face of the knowledge of the morphology of the test of Temno- 

 pleurus which has been attained since their time. 



Forbes thus diagnosed Temnechinus :—'' Body more or less spherical; ambulacral 

 and interambulacral segments developed, bearing on their plates, whose sutural margins 

 are mostly excavated, tubercles of various sizes. Vent central ; genital disk sur- 



* MartinDunoan, Journ. Linn. Soc, Zoology, vol. xvi. p. 343. 



t D u n a n and S 1 a d e n. Pal. Ind., Fossil Eohinoidea of Sind, Part II. plates ix, x, p. 36 et m 

 t Op. eit. p. 40. ^ ' ' i- a- 



