from the Island of Malta. 61 



always in small detached b.eds of inconsiderable extent, which 

 do not extend into the interior of the island. The deposits of 

 .Bonifacio and Saint-Florent were the only ones visited by M. 

 Collomb*. The rock is a light-coloured limestone, sometimes 

 white and soft, or hard and cherty, and contains an abundance 

 of small quartz pebbles derived from the decomposed granite. 



H. Description of the Fossil Maltese Echinoderms. 

 Cidaris Miletensis, Forbes MSS., n. sp. PI. IV. fig. 1 a-c. 



Test oblately spheroidal, much depressed at both poles; am- 

 bulacral areas undulated, depressed in the centre, with an 

 elevated marginal row of close-set tubercles on each side of 

 the areas ; poriferous avenues of the same width as the areas ; 

 iuterambulacral areas rather prominent, with two rows of 

 primary tubercles, about six in each row ; mammillary emi- 

 nences large, each with a circle of boundary granules ; spines 

 nearly the diameter of the test in length, tapering from the 

 base to the apex ; mouth-opening very large. 



.Dimensions. Height y^ths of an inch; transverse diameter 

 If-Q inch. 



Description. This is a very rare Urchin in the Maltese beds. 

 It has an oblately spheroidal figure, and is much depressed at 

 both poles ; the ambulacral areas, with the poriferous zones, are 

 gently undulated ; they measure together /^ihs of an inch in 

 width ; the areal band is depressed in the middle, and its 

 elevated margins are covered with two rows of large equal-sized 

 close-set granules ; internal to these are two rows of much smaller 

 granules, and down the centre is a depressed furrow : the pori- 

 ferous avenues lie likewise in depressions, bounded internally by 

 the marginal granules of the ambulacral areas, and externally by 

 the encircling granules of the primary tubercles : the inter- 

 ambulacral areas are 3^ times the width of the ambulacral ; they 

 form rather prominent convex portions of the test, with from 

 five to six rows of primary tubercles in each of the two rows of 

 these areas : the areolas are large and prominent, the summits 

 are smooth and without crenulations, and the tubercles, which 

 are proportionately large, and with a very small perforation in 

 their summit, stand well out from the body : a circle of larger 

 granules surrounds the base of the mammillary eminences; 

 these circlets are each complete in the two superior tubercles, 

 but one series is common to two tubercles in those near the 

 mouth ; the boundary in all, however, is defined, as none of the 



* Bull, de la Soc. Geol. di- France', torn. xi. p. 67 et seq., '2 MTU-. 



