16 Proceedings of the Biological Society of Washington. 



Paraperipatime (Paraperipatus) and Peripatopsina? ( Peripatopsis) ; but 

 Professor Bouvier is inclined to admit only two subfamilies, one includ- 

 ing Peripatoides and Ooperipatus as its first and Opisthopatus as its 

 second section, the other including Paraperipatus as its first and Peri- 

 patopsis as its second section. 



While by this arrangement one gets a very good idea of the interrela- 

 tionships of the Old World forms, the disposition of the American 

 species is not quite so satisfactory. The genus Peripatus as understood 

 by Professor Bouvier, including as it does thirty diverse species ranging 

 throughout tropical America, is unwieldy and does not lend itself readily 

 to the solution of problems in zoogeography. 



But Professor Bouvier has indicated a number of lines along which the 

 genus Peripatus naturally falls into smaller units, and these smaller units 

 are found to agree in their distribution as well as in their systematic unity 

 with accepted genera belonging to other classes of animals. 



It seems advisable, therefore, to recognize these smaller units as in 

 reality of generic rank. 



Mesoperipatus Evans. 



Genotype. — Peripatus tholloni Bouvier, 1898. 



Diagnosis. — The anal glands of the males open in front of the anus in 

 a common groove; there are three pedal papilla?, two anterior and one 

 posterior; the creeping pad has three bands; the nephridial tubercles of 

 the fourth and fifth legs are situated beyond the third band of the creep- 

 ing pad. 



Distribution. — French Congo. 



Included Species. — Mesoperipatus tholloni (Bouvier). 



Oroperipatus Cockered. 



Genotype. — Peripatus lankesteri Bouvier, 1899. 



Diagnosis. — The anal glands open in front of the anus by two distinct 

 orifices; there are from four to seven pedal papillae; the creeping pad 

 has at least four bands; the nephridial tubercles of the fourth and fifth 

 legs are included in the third band of the creeping pad. 



Distribution. — Pacific watershed of tropical America, from Tepic, 

 Mexico, southward to Sorata, Bolivia. 



Included Species. — 



0. balzani (Camerano) 



0. belli (Bouvier) 



0. cameranoi (Bouvier) 



0. corradoi (Camerano) 



0. eiseni (Wheeler) 



0. equadoriensis (Bouvier) 



0. goudoti (Bouvier) 

 0. intermedins (Bouvier) 

 0. lankesteri (Bouvier) 

 0. quitensis (Schmarda) 

 0. soratanus (Bouvier) 

 0. tuber culatus (Bouvier). 



The genus Peripatus as restricted by the removal of the two genera 

 described abbve may to advantage be divided into the following sub- 

 genera : 



