494 TEXTBOOK OF ZOOLOGY 



At about a year of age they are one and one-half or two inches in 

 length with a stripe down the side which gives them a peculiar 

 appearance. 



The actual breeding and copulation activities (if any) do not 

 seem to be very well understood. There is a prevailing idea that 

 the spermatophores are passed from the male to the female in the 

 autumn and held in the genital tract of the female until the suc- 

 ceeding spring when the eggs mature and pass down the oviducts. 

 The act of transferring spermatophores is described as occurring 

 in shallow water or on the muddy margin of the pond or stream 

 by the male, depositing them here while the female follows and 

 collects them into the cloaca by use of its swollen lips, the papillae 

 there, and the mucus which is secreted by the cloacal glands that 

 lie at the sides of the cloacal aperture.* 



Skeletal System 



The skeleton of these animals is classified as a bony skeleton but 

 is not completely ossified and a considerable part of it is cartilage. 

 The axial portion consisting of skull, vertebral column and ribs; 

 and the appendicular portion, consisting of the two girdles with 

 limbs constitute the essential parts of this system. The skull is 

 platybasic (flat and broad) with a marked fusion and loss of primi- 

 tive bones when compared with the teleost fish. The anterior, dorsal 

 surface of it is covered by a single, fused frontal bone, posterior to 

 which, and extending beneath and somewhat lateral to this, is the 

 large pair of ixirietals. At the anterior tip of the frontal are the 

 premaxillae which bears teeth. Just posterior to this and somewhat 

 covered by the frontal is the vomer, which also bears teeth. Both 

 the nasals and maxillae are absent. The braces, at the side of the 

 skull, are the palatopterygoid bones, each of which bears a few 

 teeth; the quadrate cartilage; quadrate hone, which articulates with 

 the lower jaw ; and the squamosal, which appears more dorsally. The 

 otic group is represented only by the prootic, a small, irregular one 

 which lies between the anterior part of the squamosal and the pari- 

 etal, and another small one, the opistliotic, which is at the postero- 

 lateral corner of the skull. The foramen viagnum (large opening) 

 is located at the mid-posterior position and an occipital condyle is 

 located at each side of it for articulation with atlas, the first vertebra. 

 The principal part of the floor of the skull consists of the large flat 



•Helpful Illustrations of the urinog-enital systems of Necturus may be found 

 In Stuart: Anatomy of Necturus maculosus, Denoyer-Geppert Co., Chicago. 



