8 The Craspedosomatidse of North America. 



stated diagnostic character, and has been used in the following- 

 synopsis of orders. So various are the adaptations of legs in 

 different parts of the body to assist in copulation, that the weight 

 of the principal distinction on which the group Oniscomorpha 

 rested has its relative importance somewhat diminished. Others 

 of its characters are evidently coordinations with its habit of 

 rolling into a sphere, and are not necessarily to be interpreted as 

 evidences of a diversity of origin. 



Synopsis of Orders of Chilognatha. 



Body composed of not more than 13 distinct segments; male copulatory or- 

 gans several-jointed, situated at tlie posterior end of the body. 



Order Oniscomorpha 

 Body composed of at least 19 segments. 



Males witli the legs of the seventh segment unmodified; external seminal 

 ducts long, divaricate, beset with whorls of setae... Order Limacomorpha 

 Males with one or both pairs of legs of the seventh segment transformed 

 into copulatory organs. 

 Males with eight pairs of legs in front of the 4-5-jointed copulatory or- 

 gans, which replace the posterior pair of legs of the seventh segment 

 and the anterior pair of the eighth; segments 1-5 each with a sin- 

 gle pair of legs Order Colobognatha 



Males with seven pairs of pre-copulatory legs ; copulatory organs not more 

 than 2-jointed, replacing one or both pairs of legs of the seventh 

 segment. 

 External seminal apertures appearing as perforations of the coxae of 



the second pair of legs Order Merooheta 



Coxee of second male legs imperforate. 



Labrum with a median sinus ; segments 1-5 with one jjair of legs 

 each; external seminal ducts wanting, the apertures located at 



the base of the second pair of legs Order Anocheta 



Labrum with a median tooth; segment 3 or 4 footless; external 

 seminal ducts present. 

 Pleurae entirely obliterated; legs 7-jointed; external seminal 

 apertures through paired, imjoiuted; external ducts inserted 



at the base of the second male legs Order Diplocheta 



Pleurae nearly free; legs S-jointed; external seminal aperture 

 single, through a 2-iointed external duct inserted at the base of 

 the second male legs Order Monocheta 



Notes on Specimens and Types. 



As Lysiopetalidse and Chordeumidse the American species of 

 this family have been subject to more revision than those of any 



