113 FISH GALLERY. 



Sandy Ray {R. circularis), the Cuckoo Ray (/?. miraletus), the 

 Common Skate {R. batis), the Flapper Skate [R. macrorhynchus) , 

 the Burton Skate [R. marginata), and the Shagreen Skates [R. 

 fuUonica and R. vomer). Some of these species, especially the 

 Skates^ attain a considerable size, the disk measuring six and even 

 seven feet across. All are eatable, and some of them regularly 

 brought to market. Teeth are exhibited in Table-case C. 

 Tase 44.] The TrygonidcE, or Sting-Rays (Cases 43, 44), are as numerous 

 as the Rays proper, but they inhabit tropical rather than temperate 

 seas. The species armed with a spine use it as a weapon of defence, 

 and the wounds inflicted by it are, to man, extremely painful, and 

 have frequently occasioned the loss of a limb. Some forms, 

 however [Urogymnus, Case 43), are devoid of that caudal weapon. 

 The genus Trygon is numerous in species, one of which [T. pasti- 

 naca) occurs on the south coast of England. Large specimens of 

 T. sephen and T. uarnak (fig. 97), and of a New- Zealand species 

 {T. Lrevicauda) , are exhibited on stands opposite Case 42 and in 

 the corridor leading into this Gallery. 



The Myliubatidcs (Case 44), also called Devil-fishes, Sea-devils, 

 or Eagle-Rays, are generally of large size, inhabiting temperate and 

 tropical seas. The tail is very long and slender. Some genera 

 {Cephaloptera, Bicerobatis) possess a pair of singular cephalic 

 processes, which generally project in a direction parallel to the 

 longitudinal axis of the body, but are said to be flexible in the 

 living fish, and used for scooping food from the bottom of the water 

 and conveying it to the mouth. Some of them, if not all, attain an 

 enormous size ; specimens weighing 1250 pounds, or measuring 20 

 feet in width, are on record. In the Myliobatina the dentition 

 consists of perfectly flat molars, forming a kind of mosaic pave- 

 ment in both the upper and lower jaws — a most perfect mechanical 

 arrangement for crushing alimentary substances. Examples of the 

 dentition are exhibited in Table-case C. 



CYCLOSTOMATA. (Case 44.) 



Their skeleton is cartilaginous and notochordal, without ribs 



and without real jaws ; the skull is not separated from the vertebral 



column. Limbs are absent, and the body is eel-like. The gills 



are in the form of fixed sacs, without branchial arches, numberingj 



