FOSSIL AND EECENT LAGOMORPHA. 505 



R bbit, from the medial side, is erroneous. The process T, "place of the real Hallux," 

 is the tuberosity of the Metat. II; with this tuberosity neither the tarsale 1 nor 

 the rudiment of the Metat. I come in contact, and therefore they cannot form a 

 connection with it. The proximal process of Metat. II, numbered 1 (= place [_SteUc] of 

 the real os tarsale primum), represents instead the rudimentary Metat. I (see PL 38. 

 figs. 5 and 6 I), which in young Lepus is distinct, but afterwards becomes fused w'ith 

 Metat. II. Tarsale 1 is visiljle in the vouns' llabbit in a cartilairinous condition *, 

 but in this species and in a Sylcilagns fi-om Bogota, in both of which I hav^e been able 

 to examine various stages, I have neither observed au ossification of it, nor a fusion 

 W'ith the rudimentary Metat. I, as assumed by Ivrause and by Leche. It gradually 

 shrinks and apparently is absorbed f. It is quite possible that in some species a fusion 

 may take place as a rule or exceptionally ; but I deny it to have been demonstrated in 

 the Rabbit, in which it is said to be the rule. Professor Howes informs me that he too 

 has searched in vain for evidence of this. 



2. Ftision of Tarsale 2 vjith Jlet a tarsale II. — A fact hitherto not noticed in 

 Lagomorpha is the fusion of tarsale 2, the mesocuneiform (e, of my figures) with 

 Metat. II. This fusion takes place in Prolagns (PI. 38. figs. 17, 27 a), in Lagoinys 

 (PI. 38. Hgs. 16, 26 (e,)), and in som^ Leporidse. In Nesulagus Netscheri (PL 38. fig. 23), 

 the figured specimen of w-hich is not adult, the fusion is not quite complete ; in the older 

 specimen at the Ley den Museum I saw it was complete. In a specimen of S/jlvilagus 

 hrasiUeiisis from Lagoa Santa, the property of the Copeuliagen Museum, tarsale 2 is 

 fused in the right limb and distinct in the left ; in an incomplete limb of the same 

 species in the Royal College of Science, London, the fusion is complete. 



3. Frcecuneiforyne. — As in the case of tlie vesalianum carpi (see pp. 501-3). my 

 attention was arrested by an accessory bone in Prolagus sardus through a small facet on 

 the tibial side of the proximal termination of Metat. II, or rather of Metat. I, since, as 

 shown before, this part is occupied in the young by the rudimentary Metat. I, which later 

 on becomes fused with Metat. II (PL 38. fig. 1", pe; fig. 27 a, facet on the upper left side 

 of Metat. II). This is the region which corresponds to the insertion of the muse. tib. 

 posticus, and therefore the ossicle, indicated by the facet, is tlie so-called distal prte- 

 hallux, or Baur's " klauenartiges Gebilde." Winge has denied the existence of this ossicle 

 in Lepus and Lagomijs \, but I have found it in both families, and, as we shall see later, 

 it has been met with as a rare occurrence even in Ijcpus europccus. In Laijomi/s it 

 articulates (PL 38. figs. 15, 16, 26 pc) by a smaller facet with the navicular as well, 

 and lies in the distal continuation of a much larger ossicle (fig. 26, ti), which articulates 

 with the navicular and the astragalus. The latter is undoubtedly Baur's and Leboucq's 

 "tibialc" (the proximal ossicle of Von Bardeleben's " prfehallux "). 



I find the smaller, distal, ossicle in the following Leporidre, viz. iu Nesolagus 



* See Leche, iu Bronu's Klass. u. Ordn. d. Thierr. vi. v. 28"^' Lief. pL xevi. fig. 3 (1S85). 



t Retterer (Cump.-reud. et. Mem. Soc. Riol. (lU) i. p. 807, 18!»4) regards the ossicle, whicli I with others hold to be 

 a nidinientary iletat. I, as tarsale I, deuyiiig- all trace of the foriaer. The presence of a cartilaginous tarsalo 1 in 3'oiing 

 Rabbits is easj- of observation, but presumably it was not yet chondrified in the stages examined by Retterer. 



j H. Winge, " .Jordfuudne og uulevende Guavere," E ilu.seo Lundii, i. p. 1G9 (1857). 

 SECON]) series. — ZOOLOGY, VOL. VII. 70 



