42 THE TERTIARY FOSSIL ECHINOIDEA 



The genus is close to Macropneustes, differing in the presence of a subanal fasciole 



only. 



Dames* notices the doubtful distinction between Peripneustes and Euspatangus, 

 and doubts whether the concave petaloid ambulacra of the former genus are sufficient 

 to separate it from Buspatangus. This applies very well to the form which he has 

 called Peripneustes brissoides, Leske, sp., from S. Giovanni, Ilarione ; but in the 

 species about to be described the Peripneustic characters are much more fully 

 developed than in the Italian specimen. On the other hand, the distinction from 

 Macropneustes, a genus well represented in the Egyptian Nummulitic series, is only 

 that of the presence of a subanal fasciole in the Eastern form f. 



1. Pkkipneustbs insignis, Duncan & Sladen. Plate V, Figs. 1-4. 



The specimen is 79 millim. in length ; and the relative dimensions are as follows : — 

 Length to breadth 1 : 0-87, height 1 : 0-608. 



The test is large- and thick, somewhat heart-shaped, longer than broad and broader 

 than high, tumid and subhemispherical in vertical outline above the rounded-off 

 margin. Abactinally the greatest breadth is central, and the test narrows decidedly 

 behind and less so in front, where the margin is broadly furrowed. Actinally the 

 posterior narrowing is less than above the margin, and a subanal groove exists, which 

 with its tumid sides gives a broad and swollen appearance to the posterior part ; the 

 margins are rounded, but less so than elsewhere in the line of the ambulacra and 

 especially of the postero-lateral. 



Abactinally the highest point of the test is behind the centre, and on the tumid 

 posterior interradium between the postero-lateral ambulacra. There is a gradual slope 

 forwards at first, and then a sharp one to the margin ; but the slope backwards is more 

 gradual, the curve being greater until a line between the ends of the postero-lateral 

 ambulacra is reached, where a decidedly oblique truncation occurs, its slope being 

 downwards and a little forwards. 



The apical system is slightly excentric in front (-2 part of the whole length in 

 front of the centre) and is in a little depression ; it is small, and much longer than 

 broad. The generative pores, four in number, are close together, the anterior pair 

 being the most approximated and the posterior rather wider apart ; they are large 

 and are at the summit of low crateriform eminences. 



The ocular plates are large and distinct, and are slightly sunken below the level 

 of the generative plates. The madreporic body, in relation with the right anterior 

 generative plate, is placed between the postero-lateral generative plates and extends 

 backwards beyond them, gradually widening so as to separate the posterior ocular plates ; 

 it narrows and ends just behind the line of the posterior edge of the posterior ocular 

 plates, causing widening of the posterior interradium there. The surface of the madre- 



• Palaeont. 1877, p. 72. 



t De Loriol, Monog. des £ohin. numm. de l'£gypte, 1881, p. 127 et seq. 



