1914.] NATURAL SCIENCES OF PHILADELPHIA. 285 



CONTKIBUTION TO THE ANATOMY OF THE ILYSIID^. 

 BY JOSEPH C. THOMPSON, SURGEON, U. S. N. 



Three species of this family have recently been the subjects of an 

 autopsy. A few additional secondary characters have been learned, 

 but none were of the primary importance of those already known, 

 and which have been employed by Mr. Boulenger to maintain the 

 group as a family. 



The salient character found to be common to the three species 

 studied, was the comparatively large diameter of the segment of the 

 posterior vena cava that is just caudad to the heart. A generic 

 character of rather an unusual nature was found in Cylindrophis, 

 consisting of a bridge of connective tissue in the floor of the mouth, 

 that extends between the sheath of the tongue and the lip. 



Ilysia scytale (Linnseus). 



This species has been made the subject of several pages by Dr. 

 Beddard.^ The characters of an example just studied conform with 

 those touched on in the article, with the exception of the position 

 of the liver. By Dr. Beddard, this organ was found to commence 

 "just at the heart as in Vipers. " In the present example the anterior 

 tip of the liver Avas 37 mm. posterior to the apex of the heart. 



A comparison of the measurements brings out the point that the 

 only difference between the two specimens is in the position of the 

 liver. 



Specimen. — 



Collection of Brit. Museum 



Dr. Beddard. Exchange Series. 



Male. Female. 



Sex. mm. Percent. mm. Percent. 



Total length 495 100 480 100 



Apex of heart 115 23.2 125 26 



Liver, anterior tip 115 23.2 162 33.7 



Liver, posterior end 293 59 295 61.5 



Gall-bladder 356 71.8. 345 72 



Kidney, right: 



Length 23 20 



Distance from cloaca 21 30 



Kidney, left: 



Length 21 15 



Distance from cloaca 11 21 



1 Proc. Zool. Soc. London, 1906, vol. I, p. 31. 



