An American Terrestrial Leech. 121 



twenty-eighth entire annulus and the female opening on the 

 thirty-third. 



Within the buccal cavity is a prominent circular fold. 

 Maxilla) three, minute, .5 mm. to .66 ram. in length, each with 

 an armature of twelve to fifteen bicuspid teeth. The pharynx 

 presents ten to fifteen longitudinal folds, the number varying 

 in different parts, with an average of twelve or thirteen. 



I have seen no specimens of Semiscolex grandis, Verrill, 

 but draw from the author's description distinctions in the 

 number of the annulations ( " about ninety " in grandis ), the 

 presence of maxillre, the positions of the sexual orifices (in 

 grandi.^ in the twenty-fifth and thirtieth annuli respectively), 

 and in the color markings, — grandis being, in Verrill's speci- 

 mens, without stripes, but spotted or blotched with dark. 



ANATOMICAL NOTES. 



The genus Semiscolex, to which this species unquestionably 

 belongs, was described by Kinberg* in 1867, but has been since 

 very little discussed. It is not, in fact, again referred to in 

 any literature within my reach, except by Verrill, in the third 

 volume of the American Journal of Science (1872^ p. 136, 

 and in the Report of the U. S. Fish Commissioner for 1872 and 

 1873, p. 671. It is clearly closely allied to Aulastoma, Moqu., 

 and seems to me but doubtfully distinct. The following 

 anatomical details will help to an understanding of the rela- 

 tions of our species : 



The alimentary canal is clearly distinguishable into five 

 regions. The first is the pharynx (closely invested by muscles), 

 which extends to about the twenty-second annulus from the 

 mouth. The second is the so-called (esophagus and proventric- 

 ulus, a simple cylindrical tube without lateral sacculi, ter- 

 minating opposite the fourteenth ventral ganglion (counting 

 the subft'sophageal as the first), where it gives off two long, 

 slender sacculi which extend backward beside the alimentary 

 canal to the last testis. At the point of origin of these sacculi, 

 the canal becomes very much enlarged, the three remaining 



* Ofversigt af Kongl. Vet. Akad. Forhandlingar, xxiii, p. 357. 



