48 



Lyra situated just behind the line joining the notches on the sides of the- 

 cephalo-thorax, large and tif a more or let^s square form. 



This species is closely allied to Ft. oldonfjun, Bucliliolz. It is found, along 

 with other forms, un the Big Sap-sucker — Picus villosus. 



PTERONYSSUS FUSCUS, n. sp. 

 Fig. 6, Pl. E. 



Male. — The body is of a somewhat rectangular shapo, contracted at the 

 insertion ot the tliird pair of extremities, so that the abdomen is only about half 

 the breadth of the thora.x. Tlie total length is about -38 mm, breadth -19 mm., 

 length of abdomen -11 mm., distance between the second and third pair.s uf feet 

 •15 mm. 



The two anterior pairs of extremities are rather slender and of about equal 

 diameter throu^'liout. The first joint is triangular, and the second articulated 

 to one of the sides by its inner surface, leaving the truncated posterior end of the 

 joint free, thus giving a peculiar shouldered appearance to these two Iront pairs 

 of legs. 



The third extremity is long, with the second, thiid and fourth joints of about 

 equal diameter, the first slightly thicker, and the fifth in the shape of a somewhat 

 bent cone with the sucker attached a little to the outside of the point. Two short 

 blade-like bristles are attached, one behind the other, on the inside of tliis joint, 

 very like those in Vimorphus albidus. The fourth extremity is simple and a little 

 longer than the abdomen. 



The epimera of the first pair of legs convergp, but do not meet in a point. 

 The bristle in front of of the insertion t)f the third extremity is rather slender, 

 and assumes almost the appearance of a hair. The abdomen is rather deeply 

 indented and furnished on each side with four end bristles. The copulatory 

 suckers are close to the posterior end. 



The female is considerably larger than the male, being about -46 mm. long 

 and -18 mm. broad. It is of a somewhat oblong-oval shape, truncated at the 

 posterior extremity. 



It is found on the White-breasted Swallow — Tachvcineta bicolor. 



FIFTH SOIREE. 



FRmAV, March 10, 1882. — Notks on the Ottawa Unionid.b. F. R. Latchford. 



The family of lamelli branch mollusks known as the Unionid.x is represented 

 in every part of the worM, but with a very irregular distribution. While only 

 ten species are fuund in Europe, fewer still in Africa and about eighty in Asia 

 and the Islands of the Pacific, over five hundred have been described from North 

 America. More than a hundred of these occur in the drainage of the Ohio alone ; 

 and in Geortiia, the Ca olinas, Alabama, and the Southern and South-Westem- 

 States in general, almost every stream has its peculiar forms. Towards the north 

 and east the species become fewer and fewer, until only eleven are found in 

 Massachuetts. In Canada a much greater number has been met with by Messrs. 

 D'Urban, Bell, Billings and Whiteaves, including several species introduced 

 from the Western States through the great lakes and other avenues of water 

 comraunic ation. In a paper read before the Field-Naturalists' Club in 1880, Mr. 

 Heron noted twelve species from the vicinity of Ottawa, but at least twice as 

 many aie to be met with here, within a radius of forty miles. The very low 

 state of the wa er in 1881 atforded me f)r collecting siiecimens of the Uuionida) 



