FROM THE CORAL RAG. 187 



Description. — This urchin has been long known to naturalists, having been figured by 

 Bourguet and Knorr in their respective works, cited in the synonymy. Leske, however, 

 in his ' Addimenta ad Kleinii Echinodermatum,' first described this curious form under 

 the name Echinus toreumaticus, and gave a figure of it in his pi. xliv, fig. 2. Some 

 authors have confused this species with Klein's Cidaris toreumatica, which is quite a 

 different urchin, and forms the type of Agassiz's genus Temnopleurus. Moreover, 

 Temnopleurus toreumaticus, Klein, is living in the Persian Gulph, whilst Echinus toreuma- 

 ticus, Leske, is found fossil only in the Coral Rag. 



The ambulacral areas are narrow, and very well defined by the straight poriferous zones, 

 which form deep furrows at their sides ; they are about one fourth the width of the inter- 

 ambulacral, and have two rows of round tubercles, about fifteen in each row, very regularly 

 arranged on the margins of the areas (fig. 3/) ; the tubercles at the base are much larger, 

 and more prominent ; and on the upper surface, a zigzag line of granules separates the 

 marginal tubercles (fig. 3/). 



The poriferous zones are narrow and straight, and, in consequence of the thickness of 

 the sculptured plates, lie deeply sunk; the pores are unigeminal and oblique (fig. 3/), 

 and there are seven pairs of pores opposite each inter-ambulacral plate ; near the peristome 

 they are in ranks of threes. 



The inter-ambulacral areas are four times as wide as the ambulacral ; from the peri- 

 stome to the equator there are two rows of large, round tubercles, on smooth, prominent 

 bosses (fig. 3 a, b, c); and around the areolas circles of granules are disposed (fig. 3/), 

 which, when viewed in profile, are rather conspicuous (fig. 3 e). On the upper part of the 

 areas the plates exhibit a most singular structure (fig. 3 b,f); around the primary 

 tubercles there are a number of irregular elevations, in relief, resembling hieroglyphic 

 characters (fig. 3/) ; and although there is a considerable uniformity in the general fades 

 of the sculpture, still scarcely are any two figures alike (fig. 3 b,f). It is this structure 

 which suggested Leske's name, toreumaticus* and Goldfuss's name, hieroglyphicus. The 

 plates are thick and broad, and there are only about seven in each column ; the tubercles 

 at the base (fig. 3 a) are round, regular, and prominent, and form a remarkable contrast 

 to the toreumatic sculpture exhibited on the upper part of the areas. 



The apical disc is large, and forms a prominence on the vertex ; it is one third the 

 diameter of the test at the equator (fig. 3 b) ; the genital plates have an elongated, hepta- 

 gonal form, and are sculptured on the surface like the plates of the inter-ambulacral areas ; 

 the oviductal hole is pierced about the outer third (fig. 3 d) ; the ocular plates are promi- 

 nent and heart-shaped, the eye-hole is marginal, and the sutural lines between all the 

 elements of the disc are defined by deep depressions (fig. 3 d) ; the vent is sub-pentagonal, 

 and the madreporiform body is represented by a few granules on the surface of the right 

 antero-lateral genital plate. 



* Toreuma, (roptvfia,) any work raised in relief. 



25 



