172 ON THE niYSIOGNOMY OF SERPENTS. 



by five scries of spots in a qiiicunx ; tail lengthened in 

 jn-oportion to the dimensions of the trunk. S. 117 + 73. 

 Country unknown. 



4'' 



14. HoMALOPSis Herpeton. — An entirely anomalous 

 species, and one of the most relnarkable of seqoents for two 

 fleshy appendages, which proceed from the point of the 

 snout, and are covered with scales. Abdominal plates 

 scarcely exceed in breadth the scales, and each is sur- 

 mounted by two keels ; 35 roAvs of scales strongly cari- 

 nated. Habit, size, and form of II. Schneideri, but the 

 trunk is very thick in the middle ; the head covered with 

 small scales, and on the crown by 9 plates, among which 

 we may observe several scales of an irregular form. Teeth 

 of equal length. S. 140 + 9G. Brown, rayed with a light 

 colour. Country unknown. 



I have included the Boas in the sixth family of innocu- 

 ous serpents. They have a prehensile tail, and also the 

 faculty of entwining themselves round any object with 

 their trunk. Their scales are numerous, and the plates 

 on the lower parts are very little developed. The head is 

 thick, with strong features, and covered wuth scales, or with 

 small plates, of which the form and disposition are very 

 dissimilar ; they eyes are small, and usually have a pupil 

 horizontally elongated ; the nostrils are more or less ver- 

 tical ; the labial plates are often hollowed out by several 

 fossettes ; the lung is usually divided into two lobes, and 

 there is a hook at the anus. The species inhabit the warm 

 regions of both worlds ; they are not numerous, and most 

 of them sui'pass all other snakes in their dimensions. Se- 

 veral species frequent fresh w^ater ; others inhabit forests ; 

 and there are some of them essentially aquatic. They 

 have the habit of crushing their prey in the folds of their 

 bodies, and of breaking its bones before swallowing it. 

 This family divides itself into three generic groups. 



BOA. 



The first genus is the Boa, properly so called. In this 

 species the intermaxillary bone is unprovided with teeth, 



