Genera of Felicias and Canida3. 101 



In general form the crania resemble those of some of the 

 terriers. The brain-case is full and convex, the orbits are 

 lateral, and the muzzle is moderately elongate and narrowed. 

 The osseous surfaces are generally smooth ; and there is no 

 indication of the ridge bounding the temporal fossa above. 

 There is a deep sinus of the superior border of the foramen 

 magnum, a character above noted as occurring in a subspecies 

 included under Canis familiaris. 



I have been unable to ascertain whether the species now 

 described is one of the forms which have been referred to 

 Canis familiaris under a subspecific name. One of the speci- 

 mens was presented to the Academy many years ago by Dr. 

 Paul Goddard, under the name of lap-dog. The form of the 

 head shows that it is not one of the forms of Canis extrarius 

 hispanicus (of Fitzinger's work on Dogs), which are repre- 

 sented by the King Charles spaniel and other lap-dogs. As 

 I can find nothing concerning it in the books, I give it a pro- 

 visional specific name. 



The origin of the characters of this genus is doubtless to be 

 traced to prehistoric time, if not to an early Tertiary geologic 

 age. Perhaps some of the species-characters are of later 

 origin, such as the obliteration of the superior-border ridges 

 of the temporal fossa? and the large sinus of the foramen 

 magnum. These characters, seen in a lesser degree in a 

 domesticated true Canis, as above mentioned, are evidently 

 an adaptation to an enlarged brain — the one to the increased 

 cerebral hemispheres, the other to the protuberant vermis of 

 the cerebellum. Whether these characters are due to a pro- 

 longed domestication, and abnormal nutrition within human 

 habitations, remains to be ascertained. I remark here that 

 two crania of dogs found mummied in Egypt by Mr. Gliddon, 

 and now in the Museum of the Academy, present all the 

 normal details of structure of Canis familiaris. 



The reduction in the number of teeth has been carried fur- 

 ther, and is probably of more modern origin, in the new genus 

 to be described below. 



Di'SODUS, gen. nov. 

 The characters of this genus, already indicated in the 

 analytical Table, are as follows: — I. f ; C. \\ Pm. ■§■; 

 M. \ ; inferior sectorial without internal tubercle. The inci- 

 sive formula might with propriety read £, since these teeth are 

 shed at an early age ; and for the same reason the tuberculars 

 might be stated }, since the last one of the upper jaw is equally 

 evanescent. I, however, give the genus the benefit of the 

 possible future discovery of species in which the teeth in 

 . Ann. & Mag. N. Hist. Ser. 5. Vol, v. 8 



