90 The Irish Naturalist. April, 



narrowing of the jaw would be advantageous in many cases, 

 but besides this it may be assumed that the double row would 

 also serve certain breeds. If the lower jaw were undershot, as 

 occurs sometimes in man, the enamel of the upper incisors 

 might produce a groove in the dentine of the lower incisors. 

 The accessor incisors in the upper jaw of certain rodents are 

 familiar ; and Owen called attention to the condition of the 

 crowns in the upper intermediate incisors of the hyaena. There 

 is in each of the latter a transversely cleft crown, and a 

 division of the posterior prism vertically, so that the crown 

 has a trefoil appearance, and the hollow between the three 

 parts of the trefoil receives the pointed cusp of the tooth 

 below. The second and third incisors of the lower jaw are 

 indented externally, but " have not the posterior notched 

 ridge like the upper small incisors" (Odontography,^. 483.) 

 Bateson mentions the absence of the lower incisors in a dog, 

 with the presence of eight incisors (four on each side) in the 

 upper jaw. He notices also a C. vulpes pcnnsylvannica (B.M.) 

 with 1.2 — 2 in lower jaw, a C. vulpes with five incisors in the 

 mandible with no socket for a sixth (Schaeff.) In tame dogs 

 he records one incisor tooth absent on each side in the upper 

 jaw. It is much rarer to find an increase in the number of 

 the lower incisors than in the upper (Nehring quoted by 

 Bateson). The case of a bulldog with a wide-crowned second 

 incisor is mentioned. The main cusp was partially bifid. An 

 incisor is rarely absent in the dog ; a case is given by Hensel 

 (Bateson), in which there were two on each side as in seals. 

 It would be interesting to know whether the variety above 

 recorded occurs more frequently in certain breeds of dogs. 

 Queen's College, Galway. 



CURRENT LITERATURE. 



Lepidoptera of Co. Westmeath. 



A note by Mr. B. L> Middleton in the current number of the Entomologist 

 (vol. xxxiv., p. 102) shows that there is still work to be done in Irish 

 Lepidoptera even in so comparatively familiar a field as Co. Westmeath. 

 Among various interesting species recorded, we note with especial 

 satisfaction Leitcoma salicis and Eurymcne dolobraria, whose known range in 

 Ireland had been hitherto confined to Clonbrock, Co. Galway. 



