402 MR. G. E. DOBSON ON THE [Mar. 1, 



Genus Erinaceus, L. 



In the form of the head and body all the known species agree 

 together remarkably closely : and, as might be expected, the anatomy 

 of these parts is much the same throughout the species ; but the 

 limbs, being nearly free from the great panniculus carnosus (which 

 as it were moulds the shape of the parts included within it), vary 

 very considerably in form and relative length of parts ; and this 

 variability is accompanied by differences in their internal structure 

 not less remarkable than have been observed between the species of 

 some otiier genera of Mammalia less closely allied by general ex- 

 ternal similarity of form. 



The anatomy of the following twelve species has been examined 

 by the writer : — 



f ] . E. eu?'opceus, L. 



I 2. E. concolor, Martin. 



Palsearctic Region .<( 3. E. algirus, Duvernoy. 



I 4. E. deserti, Loche. 



l^ 5. E, tnacracatithus, Blanford. 



„ , . . T. • \ 6. E. diadematus, Wiirtt. 



Lthiopian Keeion . . ■ - xr 7 , j . 1 c; 1 

 ^ ° [ / . E. heterodactylus, Sund. 



8. E. micropus, Blyth. 



9. E. pictus, Stoliczka. 

 Oriental Region . . <( 10. E. grayii, Bennett. 



I 11. E. blanfordi, Anderson. 

 l^ 12. E. nigevy Blanford. 



These species sufficiently represent the genus ; other known forms 

 will be found to be closely related to one or other of them. 



With the exception of tiie head and tail, the skeleton of any species 

 of Erinaceus (for all resemble one another closely) resembles that 

 of Gymnura with all the processes of the vertebrae shortened and 

 the prominences of the other bones rounded off. The form of the 

 skull differs considerably : it is altogether shorter and broader than 

 in that genus ; the brain-case is comparatively more capacious, and 

 the occipital crest much less developed. In other respects, however, 

 there is much similarity ; and the dentition is evidently but a modi- 

 fied form of that of Gymnura. If the dental formula of the latter 

 be represented as follows : — 



,- 3-3 r ^— nm ^=^ m —=44 teeth 

 *• 3_3» '^^ i_i' /"«• 4—1' '"• 3—3 — ^^ LeeLllj 



then that of Erinaceus is 



. 3—3 1—1 3—3 _ 3—3 Qfi i.„„i.u 



By modifying the usual manner of writing the dental formula, 

 the homologies ^ of the teeth of the latter with those of the former 

 genus may be thus graphically expressed : — 



' As determiued by the writer on groimds which are fully stated in the 

 work referred to iu note to p. .'iSit. 



