108 RA.DI ATA. 



No. 854. Toxaster complanatus, Agass. 



^^^^^^^M From the Upper Neocomian (Lower Greensand, Cretaceous), 



^^PHi Aiixcnv, Prance, and now in the Ward Museum, University of 

 '^sfiji^^W Rochester. Price, $0.20. 



filar 



No. 855. Toxaster ampins, Desor. 



(Syn. T. complanatus, var. ampla, Agass.) From the same locality and Mu- 

 seum as the preceding. Price, $0.30. 



This entire Suite of Echinoidea, — Nos. 759-855, — includes 86 species and 

 48 genera, represented by 105 specimens. Price, packed, $40.00. 



Order 3. — Asteroidea. 



The Star-fishes well represent the sub-kingdom. The common form 

 is that of a star with five rays, which are prolongations of the body, — 

 the viscera extending into them. The dorsal and lateral surfaces of the 

 animal are covered by a coriaceous skin, strengthened by a net work of 

 calcareous plates. These ossicles have a persistent arrangement in the 

 various genera, so that they afford good evidence of the rank of the 

 owner among the Radiates, as the bones of the Reptile or Mammal do 

 among Vertebrates. There is one ossicle situated on the side of the 

 centre of the disc which differs from all the other bones in being mark- 

 ed with radiating grooves, and is called the madreporiform plate. It 

 appears to be the analogue of the stem of the Crinoid. In the centre 

 of the ventral surface is the toothless mouth surrounded by a bony ring_ 

 The eyes are generally situated at the end of the rays. In the Ophiu- 

 ridse, the long, slender, serpent-like arms are special organs of locomotion, 

 being independent of the visceral cavity ; and according to some nat- 

 uralists, the family holds the same relation to the Crinoids that the other 

 Star-fishes hold to the Sea-urchins. 



Fossil Star-fishes, though less common, have a wider range than 

 fossil Echini. They are found in every geological period, attaining their 



