NECTURUS MACULATUS. 389 



the former to an increased number of the elements involved. The ground color of the 

 skin, as may be seen on the ventral side, which is mainly free from pigment, is yellowish 

 or pinkish, but over the sides and back varying degrees of pigmentation produce diiferent 

 shades of slate color, in places with a distinct bluish or purplish tint. The deepest pig- 

 mentatiou is that of the dorsal side wliere certain densely pigmented areas form irregu- 

 larly rounded black spots upon a bluish-slate background, thus suggesting the specific 

 name of " mdculatus.^'' ^ 



The skeleton consists of several independently separable portions and, like that of 

 other Urodeles, contains a large amount of uuossified hyaline cartilage. By far the 

 largest portion consists of the vertebral column, the skull, to which is attached the hyo- 

 branchial complex, and the posterior extremities, which are attached by the ilia to a single 

 sacral vertebra. The two halves of the shoulder girdle are free from one another and 

 from the rest of the skeleton, and they, with their corresponding free limbs, form two dis- 

 tinct skeletal parts. The remaining skeletal elements are the nasal and optic capsules, 

 the two laryngo-tracheal cartilages, and the series of rudimentai-y sternebra which lie in 

 the mid-ventral thoracic region. All of these latter parts are wholly cartilaginous and 

 entirely disconnected from other parts of the skeleton. 



In arranging the descriptive material of this memoir, the above practical division of 

 the skeleton has been taken into consideration as well as the more usual morphological 

 one, and it has seemed best to arrange the subject in the order following. In this the 

 vertebral column will be first treated, together with the ribs and sternum. The visceral 

 arches and the free sense capsules will be treated with the skull, and the limbs and their 

 girdles will appear last. This brings the parts together in their topographical relation- 

 ships and will be found more practical than a wholly morphological di^^sion. 



The Vertebral Column. 



General Description. 



The vertebral column, as is the case with fishes, shows little regional differentiation, 

 since the limbs are too small and weak either to modify the motions of the trunk by the 

 muscles attached to them, or to bring their places of attachment into prominence as 

 points of leverage or support. The only gain in this respect over the condition seen in 



'Ju-st as this manuscript leaves my hands, I have received from Mr. Alexander Nielsen, of Venice, Erie county, Ohio, 

 an extensive dealer in Necturus, a .specimen having a totally different coloring from the asual one, and Mr. Nielsen, who 

 has caught thousands of specimens, writes that it is the firet of the kind he has ever seen. The ground color of this speci- 

 men is a light reddish buff, with no sugge.stion of the usual dark slate color. The back is covered with dark brown spots, 

 smaller than in the normal forms. In form and size it closely resembles the common species. 



