460 TEMNOPLEURUS. 



TEMNOPLEURIDAE. 



Subfamily Temnopleuridae Des., 1855, Syn. Eeh. foss. 



TEMNOPLEURUS. 



Temnopleurus Agass., 1841, Yal., Anat. Genre Ech. 



Test regularly arched, somewhat conical ; actinal part of test more or less 

 concave ; tubercles crenulate, imperforate, forming two principal vertical 

 rows in each area. Pores are arranged in simple rows, but forming more or 

 less undulating and irregularly arranged zones. Tin- angles of the plates 

 separated by deep lateral and vertical grooves in the ambniacral as well 

 as the interambulacral areas. The spines are long, slender, tinted, especially 

 those near the ambitus; those of the upper pari of test are shorter, though 

 proportionally equally fine and slender. Auricles broad, with high connect- 

 ing ridges and small auricular foramen. 



Temnopleurus Hardwickii 



! Toreumatica Hardwickii Gray, 1855, Proe. Zoiil. >Soe. London. 

 ! Temnopleurus Hardwickii A. A.G., 1872, Rev. Ech., Pt. I. p. 1C6. 



PI. VIII. f. 25-88; PL VIII*. f. is; PI XXV. f. 1-2; PI XXXVI. f. /;. 



This species has the solid test of T. toreumaticus. the same solid prominent 

 abactinal system, with a small anal area. The abactinal system differs from 

 it, however, in the smaller number of anal plates, and the tuberculatum of 

 the greater part of the genital and ocular plates, leaving only the extremity. 

 where the genital opening is placed, bare. In the adult the structure of the 

 sutures of the coronal plates in both the areas resembles more in its orna- 

 mentation that of Microcyphus ; but in the younger stages ii is an undoubted 

 Temnopleurus, with sharp deep furrows ; these, however, with advancing age 

 become bevelled at the sides and extremity, so that in specimens of 28 mm ' 

 we find already the coronal plates bare along the median line, and the hori- 

 zontal sutures of the plates also bare and bevelled. Each coronal plate 

 carries but one large tubercle, forming from the ambitus a single vertical 

 row of primary tubercles ; the rest of the plate is covered by small sec- 

 ondaries and miliaries, irregularly arranged, and closely filling it. The bare 

 bevelled edges of the plates form deep connected triangular pits along the me- 



