THE PENTASTOMA. 



LiNGUATULA TvENIOIDES, Rud. 

 See Plate XVII, figs. 1-6. 



Lhiguatula tamioides is also known under the names Lmguatula rhi- 

 tiariciy Pilger, and Pentastoma tamioides, Rud. 



In describing this parasite, Neiimaau's excellent description in Traite 

 des Maladies Parasitaires, page 491, has been taken as a guide. The 

 species is probably present in this country, as in two instances the larval 

 form known as Pentastoma denticulatum has been found. The larvae were 

 found by Dr. F. L. Kilborne, of this Bureau, in a rabbit, some time in 

 the summer of 1887, and once by myself in another rabbit in 1888. 



This curious parasite is classed among the Arachnids, being more 

 closely related to the spider and mite family than to any other. The 

 order Linguatulidw, to which they belon-g, is thus defined : 



Endoparaeitic aracliuids with elougate, vermiform, anuulate body. Mouth want- 

 ing jaws iu the adult state, aud surroumled by two pairs of hooks representing rudi- 

 mentary feet. No heart. Eespiration cntaueous. In it are two genera : (1) iin^ua- 

 tula, Frohlioh, which has the body depressed with dorsal face rounded and with the 

 borders crenulated. The cavity of the body forms diverticula in the lateral parts of 

 the rings. (2) Pentastoma, Rud., which has a cylindrical body and the cavity of the 

 body continuous. It is not represented in our domestic animals, unless it be a lar- 

 val form found once in the peritoneal cavity of a dog. 



Description. — The species met with in the domesticated animals has 

 the following characters : 



Body white, lanceolate, very elongate, worm-like, depressed dorso-ventrally with 

 the ventral face nearly plane aud the dorsal face convex. Anterior extremity 

 rounded, large ; posterior extremity attenuated. Cephalo-thorax short, solidified in 

 all its width to the abdomen, from which it is scarcely distinct, and which forms by 

 far the larger part of the body. Integument showing about ninety rings, larger in 

 their middle •, these make the borders of the body crenulated. Hooks acute, re- 

 curved, twice-jointed, the basal joint attenuated iu its deep part. These hooks, each 

 retractile in a pocket, are moved by muscular bundles which act iu ojiposite direc- 

 tions. Mouth sub-quadrangular, rounded at the angles; digestive tube simple, rec- 

 tilinear; anus terminal. Male, white : length from 18 to 20'"'"; width, in front, 3"""; 

 behind, 0.5"*"', provided with saccular testicles which fill the body cavity even to the 

 anterior fourth. Female, whitish grey, often rendered brown by the eggs along the 

 median line where the integument is thin and semi-transparent; length from 8 to 

 10*^"' ; width, in front, from 8 to 10""", aud behind, 2'""'. Eggs ovoid ; length, 0.09""' ; 

 width, 0.07"^'". 



Tjife history. — The female Linguatula ta^nioides lays its eggs in the 

 nasal cavities of the dog. These are scattered on the ground and grass 



69 



