8 A KEYISION OF THE TYROGLYPHID^. 



of this species, which is allied to what Canestrini has called Tyrog- 

 h/phus siro. In 1896 Felt described a mite injuring- the roots of car- 

 nations as Tyroglyphiis heteromorjjhus. This species I have seen also, 

 and retain it in the genus Tyroglyphiis. 



OCCURRENCE OF EUROPEAN SPECIES IN THE UNITED STATES. 



As regards the occurrence of European species in this countr}', I 

 have had great ditHculties in arriving at definite conclusions, owing to 

 the fact that few European writers have appreciated the importance 

 of minute characters in classification. The}^ have identified as one 

 species forms totally different and treated under different names forms 

 closely allied or identical. The greatest trouble centers around Tyro- 

 glyphvs .sh'o^ the type of the genus. Several European acarologists 

 have figured this species. Michael is later than the others, and men- 

 tions the other figures in his references. Canestrini has figured more 

 bristles than the others, and they are longer. The pair on dorsum of 

 abdomen behind middle, according to Michael, are very short; with 

 both Canestrini and Berlese they are long. Canestrini and Michael, 

 however, agree and differ from Berlese in showing a pair of short 

 bristles near the larger humeral bristles. Michael figures the male 

 hind tarsus rather short and with the two suckers barely more than 

 their diameter apart, while, according to Berlese, this joint is very 

 much longer and the two suckers are very remote from each other. 

 Canestrini's figure shows the peculiar thickened hair of the anterior 

 tarsi as arising from the preceding joint. Several European writers 

 (especially Robin, Pagenstecher, Karpelles, and Murray) have identi- 

 fied specimens of Aleuroblvsfar!n» as T. siro, and Doctor Oudemans 

 writes me that he does not know T. siro; that the specimens formerly 

 placed by him in that species are Alewohius farinse. Berlese has 

 suggested that these two species are one, the spurred male of Aleu- 

 roblus being a dimorphic form. The habitat gives no clue to the 

 species. Specimens of a Tyroglyphus are referred to elsewhere in 

 this paper which were taken from Limburger cheese, and doubtless of 

 European origin. These are not the T. siro of any author, but more 

 related to T. mycopJiagus Megn. In a collection of mites ol)tained by 

 the Department of Agriculture from Doctor Berlese is a slide labeled 

 by him as T. hmglor. The specimen seems to be T. siro as figured by 

 Canestrini and himself; the hind tarsi are not nearly as long as they 

 figure for T. longior, and I can not see any hairs or pectinations on 

 the large bristles of the bod}-. In the same collection is a slide 

 labeled T. krameri by Berlese. Michael considers this form to be what 

 he Calls T. rnycophagus Megn. Their figures show a species with very 

 short abdominal bristles, and the inner cephalic ones much shorter 

 than the outer pair. The slide has three specimens, all females, with 



