616 MR. scLATJin ON TUB [Juue 16, 



" perforated " fang of Flaps proper {t. c. p. 411), in which all other 

 maxillary teeth have disappeared and the palatal and mandibular 

 teeth are much reduced in number. In other genera of the same 

 group the posterior maxillary teeth persist and may all acquire 

 feeble grooves, as well as the anterior mandibular teeth (Olyphodon, 

 p. 313). In the Proteroglyphs adapted to life in the sea, a similar 

 series of modifications taises place. Fi'om the Aglyphodont forms, 

 in which the teeth increase in size posteriorly, we are gradually led 

 to the Opisthoglyphs, which are only to be distinguished by the pre- 

 sence of more or less deep grooves on the posterior fang-like teeth, 

 the series culminating in such forms as have the maxillary bone much 

 abbreviated, the solid teeth reduced to two or three, and the fangs 

 extremely large and deeply grooved {Miodon, i. c. p. 250). If we 

 then turn to the skull of the least specialized among the Viperidas 

 (Oausiis, t. c. p. 406) we see that the poison-fangs are situated on 

 the posterior extremity of the maxillary, close to its articulation 

 with the ectopterygoid, a condition which is identical with that of 

 the Opisthoglyphous Colubrids. It is therefore clear to me that 

 the Viperids have been derived from the Opisthoglyphs, and that 

 there is no direct genetic relationship between them and the Pro- 

 teroglyphs, contrary to the old view which represented the Elapines 

 as forming the passage between the Colubrines and the Viperines. 

 We have thus traced a nearly complete filiation, so far as the jaws 

 and teeth are concerned, between the Colubridte aglyphse and the 

 prcteroglyphse on the one hand, and between the former and the 

 Viperidte on the other. 



Mr. West points to structural differences in the poison-glands 

 between the Opisthoglypha and the Proteroglypha. It will be a 

 matter for future investigation to ascertain whether he is justified 

 in his assumption that the gland is homologous in these types or 

 whether it has not been independently developed. 



June 16, 1896. 



Sir W. H. Flower, K.C.B.; LL.D., F.R.S., President, 

 in the Chair. 



Mr. Sclater exhibited a drawing (Plate XXVIII.) of the Gnu 

 of Nyasaland, taken by Mr. Caldwell from the specimen recently 

 transmitted to him by Sir H. H. Johnston (see above p. 506), and 

 now placed in the British Museum. Mr. Sclater pointed out the 

 differences between this form and the ordinary form of the 

 Brindled Gnu (to which the specimens now living in the Society's 

 Gardens belonged), which consisted mainly in the generally 

 brownish colour of the fur and the broad whitish band across the 

 face above the eyes, and proposed for it the subspecific name Con- 

 nochcetes taurimis joJmstoni. From the British-East-African form 



