Geological Society. 



143 



Dimensions of the type (measured in the flesh) : — 



Head and body 190 mm. ; tail 170; hind foot 36 ; ear 23. 



Skull: greatest length 46-4; condylo-incisive length 41-4; 

 zygomatic breadth 25 ; nasals 16o ; interorbital breadth 

 10-5 ; palatilar length 17 ; palatal foramina 3-8 X 2 ; upper 

 tooth-series (crowns) 7'6. 



Hah. Lamarao, Bahia, about 70 miles north of Bahia City. 

 Alt. 300 m. 



Type. Adult male. B.M. no. 3. 9. 5. 86. Original 

 number 1508. Collected 16th June, 1903, by Alphonse 

 Robert. Presented by Okifield Thomas. Fourteen speci- 

 mens. 



" Inhabits the catinga forest/' — A. R. 



Tliis subspecies differs from true albispimis by its less 

 rufous sides, its shorter broader-faced skull, and its more 

 proodont incisors. The hind foot of alhispinus was described 

 by Geoffroy as being 45 mm. in length, but Dr. Anthony 

 informs me that this was an error, and that the hind foot of 

 the type only measures 38 mm. (c. u.), 35 mm. (s. u.), while 

 the two Geneva specimens also only have the hind footi 

 36-37 mm. (s. u.). In this respect, therefore, there is no 

 difference between alhispinus and sertonius. 



PilOCEEDlNGS OF LEARNED SOCIETIES. 



GEOLOGICAL SOCIETY. 

 March 9th, 1921.— Mr. E. D. Oldham, F.R.S., 

 President, in the Chair. 



The following communication was read : — 



' The Bala Country : its Structui'e and Rock-Succession. By 

 Miss Gertrude Lilian Elles, M.B.E., D.Sc, F.G.S. 



The lithological and faunal sequence is as follows : — 



Graptolitic 

 Shelly faunas. faunas. 



'Zone of Monograptu* 



Cwm yr ^then Shales. 



Hirnant Grits and Mud- 

 stones, 300 feet, with local 



I Hirnant Limestone. 



; Moel-y-Ddinas Mudstones, 



] about 250 feet. 



I Moel-Fryn Sandstones, at 



I least 1000 feet. 



I Rhiwlas Limestones and 

 Mudstones. 



crispns. 

 Zone of Monograpfr 

 sedgivkki. 



Orfhis-hirnantensis', 

 fauna. 



Phacops-mucronatut 

 fauna. 



Ph illipsinella-para- 

 bola fauna. 



