iV ( 



I I 



!.^ 



m 



N't- 



r, 



550 



MCNOGKAPHS OF NORTH AMERICAN RODENTIA. 



Intestines muny (nbout eleven) times ns long as the body. Ccccum very largfi 

 (as long as the body). Outlets oi genito-urinary and digestive organs distinct 

 from each other (compare Castorid^). Testes aiidominal. Os penis very 

 large, cleft at the end. Urethral glamts few and simple (no other pcrinseal 

 glands ?) 



For other characters, derived from the external structure, and properly 

 to be considered as rather pertaining to the genus than to the tamily, see 

 under next head. 



As may be gathered from the foregoing epitome of the more salient 

 anatomical characters, the present is a remarkably peculiar group, entitled 

 to full family rank, if not to still higher appreciation. Like the equally pecul- 

 iar Castorida, it has, as one author has remarked, long proved a stumbling- 

 block in the way of a systematic arrangement of the Rodents ; but for no 

 other reason, as it seems to me, than because authors long regarded the type 

 of structure as only significant of a genus, a place for which was to be 

 found perforce among the then established families, instead of recognizing its 

 claims to higher valuation. It would be idle to recount the various forced 

 associations to which the family considered as a genus has been subjected.* 

 The general tendency has been, however, of late years at any rate, to associ- 

 ate Haplodon more or less intimately with Castor, and to refer both genera to 

 the Sciurine series, if not to the Sciurida itself Thus, In 1858, Professor 

 Baird made Castor and ^'Aplodoniia^' together a subfamily Castorina of the 

 family Sciurida,\ inquiring pertinently whether the two were not typical of 

 as many distinct subfamilies, themselves forming a group of full family rank. 

 Professor Brandt had already, in 18.55, placed the genus next to Castor. In 

 1864, Herr W. Peters discussed the genus, comparing the skull with that of 

 Arctomys, and noting the strong resemblance observable in many respects ; 

 he is considered by Mr. Alston t to have "definitely established" the Sciurine 

 affinities of the genus. In 1866, Professor Lilljeborg (I. s. c.) first, as far as 

 I can ascertain, cleared the way for the required improvement in classification, 

 by raising the genus to the rank of a family, which he called Haploodontidx, 

 and placed next after Sciurida ; although, as Mr. Alston (/. i. c.) observes, he 



* For examplu, in 1840, Schinz threw "Aplodoutia " into his VII ■• family " of Gttrai, " Cmleularia " 

 wliioh coDBisted of an odd Jamble of Baptodon, "Atcomj/i" (=OeoMj)<), Tkomomtt, SipkMiM, Clnomgt^ 

 Spalax, and varlouB other burrowing Rodent* ; ua gacb, Iwing beneath eerions criticism. 



t Baird's family Sdvrida, however, incloded the Uariue' family ifyoiMo, traated as a sabfamlly 

 MfoxiHa. 



t P. Z. S. 1876, 66. 



