FOSSIL AND EECENT LAG03I0EPHA. 515 



The Caprolaxjvs group (A) differs from the Lepus group by the following characters, 

 part of which, as said above, it shares with Paheolagiis aud with the Lagomyida? : — 



Lesser specialization for speed, and in correlation with this, lesser develoi^ment of organs 

 of sense (sight, smell, hearing). Fore and hind feet comparatively short and subequal. 

 Ears short. Eves smaller. Tail very short or missing. 



Cranium, depressed above, anteriorly and posteriorly very little bent downward. Upper 

 contour of frontals and posterior part of nasals almost horizontal (exc. Orijctolagus). 

 Inferior border of orbit — formed by malar bone — shorter than in the Lepus group ; sinus 

 on the lateral face of malar not advancing so far forward (exe. in Oryctolagus). Upper 

 border of zygoma l)ent inward, inferior Ijorder arched outward (exc. in Oryctolagus). 

 Posterior appendix of zygoma elongate and, in correlation, mandibular condyloid process 

 elongate also (exc. in Oryctolagus crassicaudatus) . 



Infraorbital foramen larger than in Lepus and its immediate neighbourhood almost 

 devoid of reticulation. The heavier skull in the X group is in evident correlation with 

 the different mode of locomotion. The following cranial characters of A are apparently 

 in correlation with the less develojoed organ of smell : — Horizontal portion of os palatinum 

 comparatively well develojied ; interpterygoid fossa and choaufe comparatively small. 

 Foramina incisiva comparatively narrow and short. Anterior part of nasals less inflated 

 than in Lepus. In correspondence with the smaller eyes, the orbits are comparatively 

 small, and the orbital processes more or less reduced. 



In conclusion, I wish to express my very special obligations to Prof. Howes for loan 

 of material, valuable suggestions, and the pains he has taken in connection with this 

 memoir. 



EXPLANATION OF THE PLATES. 



Plate 36. 



Fig. 1. Cnprolayus [Oryctolagus) cunkuhis (Linn.), jiiv. Riglit maxiHary ; cl. 3-m. 2. 



Fig. 2. Plemidapis Dmibrei, Lem. Riglit upper molar. Enlarged copy from Bull. Soc. Gcol. France, 



3. xix. (1891) pi. X. fig. 62 w. 

 Fig. 3. Pelycodus helveticus, Riit. Right upper molar. Enlarged copy from Abh. Schweiz. Pal. Ges. 



XV. pi. fig. 12 ff (1888). 

 Fig. 4. Prolaf/us sardits (Wagn.). Left maxilla with deciduous teeth (d. 3-d. 1) and first molar. Monte 



San Giovanni (Sardinia). Br. Mus. G. D. No. i\I3464. 

 Fig. 5. Caprolagus {Oryctolagus) cuniculus (Linn.); slightly older than fig. 1. Right maxilla; d. 3- 



m. 2 ; alveolus of m. 3. 

 Fig. 6. Titunomys Fontannesi (Dep.). Second (last) right upper molar (m. 2), almost disused. Middle 



Miocene. La Grive-Saint-Alban (Isere), as all the other specimens of this species *. 

 Fig. 7. THanomys Fontannesi (Dep.). First right upper molar Cm. 1). 



Fig. 8. THanomys Fontannesi (Dep.). Posterior right uj^per premolar (p. 1). Br. Mus. G. D. No. 5268 

 Fig. 9 THanomys Fontannesi (Dep.) ? Second right upper premolar (p. 2) ? * 

 Fig. 10. Prolagus ceningensis (Kon.). The three left upper premolars (p. 3-p. 1) of young specimen. 



Middle Miocene. La G rive-Saint- Albau, as all the other specimens of this species. Br. 



Mus. G. D. No. 5234. 



* The figures marked thus are from specimens in the possession of the author. 



71* 



