Dec. 1896.] Dyar : LiFE-HisTORiEs OF N. Y. Slug Caterpillars. 113 



Special Structural Characters. 



Dorsal area broad, narrowing before to a rounded margin on joint 

 3, narrowing behind to a point in the tail-like termination of joint 13. 

 Lateral area absent, the subdorsal and lateral ridges at first closely ap- 

 proximate, later fused into a single, sharp, high, rounded ridge. Sub- 

 ventral area broad, forming all the sides, perpendicular, flat or hollowed, 

 highest in the middle, diminishing to almost nothing at both extremities. 

 Subventral ridge very slight, just indicated at the lower edge of the 

 body. Primitive first stage absent, the warts present in stage I reduced 

 by degeneration, bearing two setse, uniformly developed ; in the later 

 stages disappearing, the rudimentary setae persistent. Subventral row 

 represented by small setae. Both the lateral and subdorsal warts are 

 situated on the single subdorsal ridge. Depressed areas strongly de- 

 veloped but scarcely sunken, flat, plate-like, shagreened and with angu- 

 lar margins ; the dorsal row (i ) elongate transversely, hexagonal, the 

 addorsal (2) small, rounded triangular; those of the lateral area want- 

 ing; subventral plates fully developed, rounded angular, the upper sub- 

 ventral (7) large, ovate, the lower (8) rounded triangular; two other 

 small rows above the subventral edge (9; and near the spiracles (10). 

 Skin at first almost smooth, but soon covered with granules which are 

 flattened, appressed and rounded and appear as if overlapping like the 

 scales on a fish, on the sides from below upward, outwardly from the 

 middle of the dorsum to the upper side of the subdorsal ridge where the 

 two directions of scaling meet. The scaling is only present on the lat- 

 ticed ridges between the closely set, slightly sunken armor plates (meta- 

 morphosed depressed areas). There is a slight hump or rounded angu- 

 lation on the ridge at joints 7-8, but this may be absent or there may 

 be two such humps, the second at the junction of joints 8 and 9. Just 

 under the edge of the subdorsal ridge from side view is a series of 

 glandular spots which can secrete drops of a clear odoriferous fluid. 

 They are situated above and a little before the upper side of the large 

 intersegmental plates (7) and appear in the cast skin as round beads. 

 It is possible that they represent the depressed spaces of lateral area. 



The coloration is adapted for concealment, the green ground work 

 variously patched and spotted with yellowish and brown being obscure 

 on the leaves toward autumn. The peculiar square box-like shape, pro- 

 duced by the union of subdorsal and lateral ridges, may be of use in sug- 

 gesting to its enemies an appearance unlike that of most insect larvae, 

 more unusual indeed than the majority of Eucleidse. 



