PHIOMIA SEERIDENS. 171 



Behind the incisors there is a long sharp-edged diastema about 5*5 cm. in length- 

 The first cheek-tooth is small and laterally compressed, with a high anterior cusp, 

 slightly bifid at the summit, and a smaller posterior one, which seems to belong to the 

 cingulum ; there is also a slight cingular prominence on the front of the tooth. The 

 next tooth is large and complex. The anterior half consists of three cusps: one 

 anterior, with a small sty lid closely united to it in front; the other two arranged 

 transversely. There is a small accessory tubercle on the posterior slope of the outer of 

 the two cusps. This anterior portion of the tooth is separated from the wider posterior 

 part by a deep valley, behind which there are two large and closely united cusps 

 arranged transversely and a small accessory posterior tubercle. The nature of 

 these two cheek-teeth is open to some doubt ; probably they are deciduous molars, 

 though this is not absolutely certain, and although the jaw has been carefully cut 

 away beneath the larger tooth no trace of any germ of the replacing tooth can be seen. 

 On the whole, it seems that Schlosser is possibly right in his surmise as to the nature 

 of this specimen, and it may be considered as having belonged to a young individual 

 perhaps of one of the smaller species of Palceomastodon ; but since it is very small 

 and there is some doubt as to the nature of the teeth, the generic name Phiomia may 

 be retained till further material is available. 



C. 10007. Anterior portion of left mandibular ramus, with incisor and two cheek-teeth. Type 

 specimen described and figured, loc. cit. ; also PI. XVIII. figs. 4, 4 A. The dimensions 

 (in centimetres) of this specimen are :— 



Extreme length of specimen, so far as preserved 14'2 



Length of protruded portion of incisor, measured along median 



border 3 app. 



Width of incisor at alveolus 1'6 



Length of symphysis 6-5 



Greatest depth of symphysis 2 



Length of diastema between incisor and first cheek-tooth . . 6 app. 



Depth of ramus beneath second cheek-tooth 3'5 



Length of first cheek-tooth 1-2 



Width of first cheek-tooth -5 



Length of second cheek-tooth 2*7 



Width of second cheek-tooth 1-3 



Iff. 8193. Plaster cast of the above specimen. Made in the British Museum. 



z2 



