PEOCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 399 



Taken as a whole we could Larclly look for a better example of a rudi- 

 meutary apparatus throughout, even to its miuor details. lu GerrJwno- 

 tus, all of the poiuts that are so feebly developed in Opheosaurus have 

 beeu carried to a still higher point, and one approaching the true Lacer- 

 tilian type, and although in this lizard the anterior and posterior limbs 

 are present, they are weaker than in other forms, such as the Iguaiiidw. 

 In Gerrhonotus the clavicles meet mesiad, and the coracoids articulate 

 with elongated facets upon a semi-osseous sternum, that has inserted 

 along its sides the hjBmapophyses that articulate above with the dorsal 

 ribs. Passing next to the examination of the pelvis, we find that 

 although some parts have been more or less suppressed or have almost 

 passed beyond recognition, we still find a rudimentary femur i^resent. 

 The fifty-seventh vertebra has suspended from its diapophyses, and 

 articulating freely with their extremities, two spoon-shaped bones, one 

 on either side; these do not meet in the median line, but are separated 

 by a space of several millimeters. The dilated extremity of each is below, 

 and from the middle point on the outside surface, rotating in a diminu- 

 tive acetabulum, we find the rudimentary femur, represented by a 

 minute cylinder of bone, rounded at both extremities. A 

 faint sutural line passing through this coty- 

 : loid-cavity indicates the division between the 

 iliuoi above and the puboischium below. Pro- ^^_-:^)J^--^ 

 fessor Mivart found this condition in some of ^*^^=5^ 



rv-y. the forms he examined, and he tells us in his jr,>.3 



Lessons in Elementary Anatomy, page 195, that "confining ourselves, 

 therefore, for purposes of comparison, to Mammals, Sauropsida, and 

 Batrachians, we find the femur under a certain aspect more constantly 

 present than the humerus. For although it is often absent when the 

 humerus is present (as in forms like Siren, which have pectoral limbs 

 but no pelvic ones), yet it is sometimes present in a more or less 

 rudimentary condition when no representative of the foot coexists with 

 it. Such is the case, e. {/., in some whales (as the Greenland whale) 

 amongst mammals, and certain snakes, e. g., Boa, and certain lizards, 

 e. g., Liaiis, amongst*the reptiles." 



In Gerrhonotus all three of the pelvic bones go to form the acetabulum, 

 the pubic elements curving far anteriorly as delicate osseous columjis 

 to meet, mesiad, in a common cartilaginous articulation. The arch is 

 suspended in a like manner from the transverse processes of a vertebra. 



Though a little foreign to our subject, it will be of interest to many 

 to know something of the character of food of this lizard, and in this 

 Professor Eiley has kindly assisted me, and sends the following diagno- 

 sis of a stomach that I sent him : « 



"The contents of stomach of Oplieosaurus ventralis consists almost en- 

 tirely of fragments of a tolerably common spider, Lycosa ruricola Hentz, 

 with a single small black seed and seed-pod of some plant, not determ- 

 inable on account of condition." 



