ASTROPECTEN. 29 



1. AsTROPECTEN CRispATtis. Plate IV, fig. 2. 



AsTERiAS, sp., Ansted, Geology, vol. ii, p. G6, woodcut. 



AsTROPECTEN CEISPATUS, Forbes, Mem. Geol. Surv. Great Britain, vol. ii, pt. 2, p. 479 : 



and Fig. and Desc. of Brit. Org. Rem., dec. i, pi. 3, fig. 3. 



This is the commonest of Eocene star-fishes, and specimens from the London Clay of 

 Sheppey are preserved in many cabinets. It has long attracted notice, but was first 

 figm-ed, without a specific name, by Professor Ansted. It seems to have been of a 

 firmer and less brittle habit than its brethren, since it is the only one of our London Clay 

 species that presents anything near completeness of shape. 



It has five triangularly lanceolate rays radiating from a broad central disk. The 

 pyritous condition in which the examples are always found, prevent our making clearly 

 out the details of its ornamentation, but apparently the dorsal surface was studded with 

 rather large paxillse. The margins of the arms are bordered by very numerous, narrow, 

 closely-set oblong plates, varying from 25 to above 35 on each side of the arms of the 

 larger specimens examined. These gently decline outwardly, where they meet with 

 similar under-plates, so that the edges of the arms seem as if somewhat compressed. All 

 the marginal plates bear at their outer and upper edges short obtuse lanceolate spines. 

 There are indications of ossicula of considerable size, and probably spinigerous, bordering 

 the narrow avenues. The greatest diameter, from tip to tip of rays, in one of the most 

 perfect specimens which I have seen (in the cabinet of Mr. Bowerbank), is two inches and 

 a quarter. The breadth of the disk in this example is one inch. The species grew to 

 a larger size. 



2. AsTROPECTEN ARMATUS. Plate IV, fig. 1. 



AsTKOPECTEN ARMATL's, Forbes, Mem. Geol. Surv. Great Britain, vol. ii, pt. 2, p. 479; 



and Fig. and Desc. of Brit. Org. Rem., decade i, pi. 3, 

 fig. 4. 



The specimen originally described and figured of this species is still the only one 

 known. It is the greater part of the under surface of a single arm. The marginal 

 ossicula bear narrow elevated ridges, upon which are impressions indicating the sockets 

 of spines. On their outer sides ai'e long, slender spines, perfectly preserved. Indications 

 may be perceived of fasciculi of short spines, in threes or fours, on the ossicles bordering 

 the edges of the avenues. It is very distinct from any other Eocene star-fish as yet 

 observed. The fragment measures nine twelfths of an inch in breadth at its base, and one 

 inch three twelfths in length. The spines and plates are respectively about three twelfths 

 of an inch in length. It was procured in the Clay of Sheppey. 



