THE CANADIAN ENTOMOLOGIST. 173 



NORTH AMERICAN THYSANURA.— II. 



BY ALEX. D. MACGILLIVRAY, ITHACA, N. Y. 



The genus Japyx has been of particular interest because of the 

 apparent absence of rudimentary abdominal appendages. One American * 

 writer says very decidedly, "Japyx has none " ; a well-known English f 

 writer considers these appendages as " represented by mere groups of 

 stiff hairs." The presence of these appendages was indicated as early as 

 1869, by Brauer, % in his description of Japyx gigas. In 1889 there 

 appeared a very important paper by Haase §, in which the rudimentary 

 appendages are distinctly shown. These appendages can easily be seen 

 in either of the species described below. 



Japyx subterraneus, Pack. 



1874, Japyx, Packard, Amer. Nat., VIII., 501. 



Head quadrangular, not broader than long. Antennae about thirty 

 joints. Prothorax narrower than the head, truncate in front. Abdomen 

 gradually broader behind, segments marked on each side with whitish 

 dots, arranged in the form of a figure six ; segments one to six rounded at 

 the sides, the seventh slightly emarginate behind, posterior angles pro- 

 duced, not spinate, eighth subequal to the seventh, longer than the sixth, 

 slightly emarginate behind, sides straight ; ninth segment one-third the 

 length of the eighth, posterior angles not produced ; the tenth segment 

 and forceps subequal in length, together equal in length to the four pre- 

 ceding segments. Right arm of the forceps broader than the left, with a 

 stout tooth on the inner margin near the middle ; in front of this tooth 

 the inner margin is convex with four small tubercles, adjacent to the 

 tooth, beyond the tooth the arm is concave and armed with tubercles to 

 the apex. The left arm is broadest at base, becoming gradually narrower 

 till a little beyond the middle, where there is a large tooth-like tubercle, 

 in front of this tubercle the arm is concave and armed with seven to 

 eight small tubercles ; beyond the tubercle the arm is convex and armed 

 with very small tubercles. 



* Packard, Standard Natural History., II, 1884, 137. 



t Lubbock., Monog. Collem. and Thys. , 1873, 205. 



% Brauer, Verh. Zool.-bot. Ges. Wien, XIX., 1869,557. 



§ Ilaase, Die Abdominalanhange der Insekten mit Berucksichtigung der Myriopo- 

 den, Morphol. Jahr., XV., 1889, 330-435 ; pis. XIV.-XV. 



