BRITISH FOSSILS. 



Decade I. Plate II. 



OOLITIC SPECIES OP ASTROPECTEN. 



[Genus ASTROPECTEN. Linck. (Sub-kingdom Radiata. Class Echinodermata. Order 

 Asteriadse. Family Asterise.) Body stellate, few (five) rayed ; no vent ; rays flat On both 

 sides, regular. Surface of body and upper sides of arms covered with paxillse. Ambu- 

 lacra with two rows of suckers, bordered by spines. Margins of the arms bordered by a 

 double row of conspicuous plates. — The genera Stellakia of Nabdo, and Asterias 

 (restricted) of Agassiz, are synonymous.] 



Fig. 1. 



ASTROPECTEN HASTINGIiE. 



E. Forbes, in " Memoirs of the Geological Survey of Great Britain," 

 vol. ii. part 2, p. 478. 



Diagnosis. A. radiis brevibus, lanceolatis, acutis^ lateribus rectis, angulis 

 intermediis obtusis ; ossiculis marginalibus quadratis, subcequalibus. 



Description. — Rays short in proportion to the rather broad flat body, 

 triangularly lanceolate, with very straight sides and pointed extremities. 

 The angles formed by their junction with each other and the body are 

 obtuse. Their margins are bordered by regular series of nearly equal 

 square plates, decreasing but slightly as they approach the apex. The 

 length of each ray is about equal to the diameter of the disk. There 

 are about 18 marginal plates in each row. The surface is covered by 

 quadrate tessellations, indicating the arrangement of the plates, which 

 probably, when the animal was alive, bore tufts of paxillse or coronated 

 spines. The specimen measures two inches in diameter. 



Affinities. — The Astropecten Phillipsii is probably its nearest fossil 

 ally, but the form and characters of its surface distinguish it con- 

 spicuously from any other British member of its genus. 



Locality and Geological Position. — From oolitic beds (marlstone) in 

 Yorkshire, precise locality not known. In the cabinet of the Mar- 

 chioness of Hastings, who has kindlv communicated it for description 

 and delineation. 



[i. ii.] c 



