BRITISH FOSSILS. 



Decade V. Plate IV. 



ECHINUS PERLATUS. 



[Genus ECHINUS. Linn. (Sub-kingdom Radiata. Class EcWnodermata. Order 

 Echinidse. Family Cidaridse.) Body inflated ; interambulacral arese composed of 

 numerous plates ; ambulacral arese about half the width of the others, and with tubercles 

 of as large a size ; pores in transverse, oblique, or arched ranks of three or four pairs ; 

 anus covered by numerous small plates, and surrounded by five genital plates, one of 

 which (the left posterior, MUUer) is considerably enlarged, and bears the madreporiform 

 tubercle.] 



• 



Diagnosis. E. biuncialis, rotundus seu pentagonus, supra granulosus^ 

 subtus muricato-tuberculatus ; ore pentagono angulis bifidis. Tubercula 

 primaria conspicua, in uirdque area bina, in singula serie ambulacri 

 circa 38, — inter ambulacri 29 — secundariis supra minoribus paucis scepe 

 nullis, subtus maximis numerosis ; granulis crebris conspicuis. Am- 

 bulacra vix latitudine dimidium interambulacrorum attingentia scepe 

 prominula. Pori in series triplices parallelas — in juniore plus minusve 

 obliquas, collocati. 



Synonyms. Knorr, Rec. des Mom. (1768), pi. E. 2. fig. 1, 2. Leske 

 apud Klein (1778), p. 92. pi. 40. fig. 7. (nisi icones illce E. gyrato potius 

 referendce). Echinus perlatus^ Desmarest (1825), Diet. Sc. Nat., t. 37. 

 p. 100. Forbes (1854), in Morris's Catalogue, 2nd edit. Wright (1851)^ 

 Ann. and Mag. N. Hist., vol. viii. 2nd ser. 274. 



Var. a, germinans^ fig. 1-4. — Pentagonus conicus, in medio inter ambulacri 

 depressus, scepe Icevigatus ; basi subplano ; angulis oris productis ; tuberculis 

 secundariis insuper paucis ; poris parallelis. — E.germina^is, Phillips (1835), 

 GeoL Yorkshire, pL 3. fig. 15. E. diademata, M'Coy (1848), Ann. Nat. 

 Hist., vol. ii. p. 410. 



Var. jS. perlatus. — Rotundus iuflatiis elevatus seu subdepressus, basi 

 subconvexo ; tubercidis secundariis numerosis magnis, granulis valde con- 

 spicuis ; poris iti series parallelas plerumque collatis. — E. perlatus. Agass., 

 Ech. Suisses (1839), t. 22. fig. 13-15. E. psammophorus^ ibid., fig. 1-3. 

 E. lineatus, Goldfuss (1826), Petr. Germ., t. 40. fig. 11. E. perlatus, 

 [v. iv.] 5 D 



