LIFE-HISTOEIES OF GAMASIffjfi.. 309 



dorsal plates, are not species at all, but are immature stages of 

 other species. 



2. That the division of the dorsal plate is, in most cases at all 

 events, a question of degree, and does not form a sound basis 

 for classification, as applied by Koch, Kramer, and others. 



3. That the dorsal plates do not grow gradually, but alter iu 

 size, shape, or development at the ecdysis. 



4. That Megnin is right in saying that the characteristic of the 

 so-called G. marginatum is simply a provision possessed by the 

 females of a large number of species. 



5. That the extent of the white margin depends upon the extent 

 to which the abdomen is distended by eggs. 



6. That Megnin is in error in saying that coleoptratormnis the 

 nymph of crassipes. The nymph of crassipes does not show any 

 divided dorsal plates which can be seen on the living creature. 



7. That in the species which I have bred there is not any inert 

 stage before the transformations or ecdyses. 



8. That in the same species copulation takes place with the 

 adult female, and not with the immature one as Megnin contends, 

 and that it is by the vulva, not the anus, 



EXPLANATION OF THE PLATES. 

 Plate XXII. 

 Fig. 1. Larva of Gamasus coleoptratomm t X about 35. 



2. Nymph of Gamasus coleoptratorum, X about 35. It is from this nymph 



that the so-called species was named. 



3. Larva of Gamasus crassipes, x about 35. 



Plate XXIII. 

 Fig. 1. Adult male Gamasus coleoptratorum, X about 35, 



2. Oaruncle and claws of same. 



3. Side view of mandible of adult female of same, X 55, rendered trans- 



parent so as to show the articulation of the movable joint, the thick- 

 ness of the chitine, &c. 



4. Organ (qy. tactile ?) depending from epistome of Gamasus crassipes. 



5. Scattered nucleated chitinous cells on the first nymphal cast skin of 



Gamasus crassipes. 



6. Next stage. Cells aggregating into groups, but still preserving a some- 



what rounded outline. 



7. Later stage. Cellulation of semitransparent dorsal shield, visible only 



on the cast nymphal skin : Gamasus crassipes. 



8. Cellulation of conspicuous dorsal shield' of nymph of Gamasus coleo- 



ptratorum. 



24* 



