Carpkntek — The Apterygota of the Seychelles. 3 



of the Seychelles. These families are easily distinguished by readily observed 

 structural characters. 



A. Jaws projecting beyond the mouth ; maxillae and labium 



developed somewhat as in typical mandibulale insects, with 

 conspicuous jointed palps. A median jointed tail-process. 



Sub-order Edotroplii. 



a. Body not flattened dorso-ventrally ; dorsal aspect of 



thorax markedly convex. Head with paired and 

 median ocelli in addition to the large compound eyes. 

 Abdominal segments 1-7 with exseriile vesicles, 2-9 

 with unjointed stylets, 10 with long jointed cerci. 



Family Machiliclac. 



b. Body flattened dorso-ventrally. No ocelli; compound 



eyes relatively small. Abdominal segments usually 

 without exsertile vesicles (on segments 2-7 in some 

 Nicoletiiuae), stylets usually on segments 7-9 or 8-9 

 only (rarely 2-9), .... Family Lepismidae. 



B. Jaws apparenily retracted within the head; maxillae and labium 



higlily modified with palps unjointed or absent. No median 

 tail-process, ....... Sub-order Entotrophi. 



c. Cerci modified into forceps, . . . Family lapygidae. 



d. Cerci elongate with sensory bristles, . Family CainjJodeidae. 



Family MACHILIDAE. 



Our knowledge of the various genera comprised in this family has 

 been vastly extended during recent years through the work of Silvestri 

 COi, '05, 'U6, '11; and Verhoelf ('10). The latter author has deemed it 

 advisable to recognize three distinct families instead of one. While the 

 characters used in this discrimination — the shape and extent of the abdominal 

 sterna and the number and arrangement of the exsertile vesicles which 

 these bear (see Plate II, figs. 19-23, 27-31 e.v.) — -are of undoubted value in 

 facilitating classification and indicating relationship, they are not of sufficient 

 importance to justify family-distinctions. The Machilidae, as generally 

 understood, form such a natural and easily recognized group of Thysanura, 

 that Silvestri is undoubtedly to be commended for following the older 

 entomologists in regarding the insects as constituting a single family. 

 Verhoeffs divisions may conveniently be regarded as sub-families— to be 

 distinguished thus — 



A. Abdominal segments all with very small sterna, and bearing at 



most one pair of exsertile Ncsicies, . . . Mei'/ierteUiiuie. 



