68 COMPARATIVE ANATOMY. 



Batrachia arid Reptilia. Kidneys compact, deeply situ- 

 ated, often firmly connected to iliac bones, when present, by 

 peritoneum, as in Chelonia and Sauria. Bladder present 

 with many Lacertilia (lizards) and Batrachia. Kidneys of 

 Ophidia not placed on same level, the right situated more 

 anteriorly than the left; the structure is more lobulated and 

 less compact than in Chelonia. 



Aves. Kidneys deeply situated, and extend from lungs 

 downward as far as rectum. The posterior surface is moulded 

 into the cavities formed by the bones on which it rests. 

 There is no pelvic cavity, and the ureters empty into cloaca. 

 (Johnson.) 



Mammalia. Form often lobulated, as in Rhinoceros, and 

 Phoccena (dolphin). The urine escapes from uriniferous tu- 

 bules into pelvis, to empty into bladder through ureter, 

 thence to be voided by urethra. 



X. 



INTEGUMENT. 



THE layer of tissue investing an animal is called the integ- 

 ument. In the embryonic condition of many of the lower 

 forms the investment is continuous over the surface of the 

 body, without any proper processes or irregularities. 



PROTOZOA. See Skeleton and Spongia. 



RADIATA. Coelenterata. Integument composed of a sim- 

 ple cellular commonly translucent, thick gelatinous layer 

 without appendages. In Aurelia (jelly-fish) it forms a loose- 

 mass, somewhat resembling connective tissue, interspersed 

 with occasional elastic filaments and muscular fibre. The 

 hydroid polyp stalk possesses two dermal layers one, inner, 

 is cellular; the other, outer, is structureless, and forms a 

 sclerous covering to the animal. 



Echinodermata. Integument more or less calcified. (See 

 Skeleton.) 



