Dec. 1896.] Dyak : LiFE-HisTORiEs OF N. Y. Slug Caterpillars. 175 



measurements given that they really were stages IV and V. Two of the 

 references include a general account of the finer external structure. A 

 general and not unnatural error has been made in considering the sunken 

 armor plates to represent the segments. Edwards and Elliot say "the seg- 

 jnents are arranged like the plates of a tortoise," Dr. Packard refers to 

 a marking •' along the sutures ... of the segments," and I have said 

 "joints 3 to 13 have each a plate." These structures are situated be- 

 tween the segments, overlapping on two adjoining ones. Dr. Packard 

 found but seven spiracles ; but he must have had before him an abnor- 

 mal larva, as all my specimens possess the usual number. 



Description of the Several Stages in Detail. 



Eg^. — Elliptical, flat, 1.8 x 1.2 mm., the skin very thin, white and 

 iridescent ; the fresh egg is transparent with a slight pale yellow tint 

 when laid on glass and becoming more opaque as the embryo de- 

 velops but not darkening in color. Reticulations rounded, obscure, 

 rarely angular, not characteristic ; the surface of the egg is slightly 

 shagreened. Another egg measured 1.7 x 1.4 x.i mm. Laid singly on 

 the leaves. 



Stage I. — Elliptical, more pointed behind than before ; dorsum flat, 

 a little arched, separated from the perpendicular sides by a ridge bearing 

 two rows of tubercles, each with two setae (Plate VII, figs, i to 3). These 

 represent the usual subdorsal and lateral rows, but situated in close ap- 

 proximation to each other. On joint 3 are four tubercles, on joint 4, 

 three, and on joint 13, three. ' A subventral row of simple setae. The 

 shape is less boat-like than the mature larva, though all the essential 

 features are indicated. Pale yellowish, a broad dark band along the 

 ridge below the skin and therefore appearing in a slightly different po- 

 sition according to the point of view. The band is connected with its 

 fellow at the ends and also by a bar in the center of the dorsum. Dorsal 

 skin smooth, depressed in gentle hollows representing the dorsal (i) 

 and addorsal (2) depressed spaces; bases of tubercles wrinkled, sub- 

 granular ; lateral (subventral) skin also smooth, with two rows of faint 

 depressions. Venter clearer yellow than the body ; head pale. Length 

 1.2 to 1.9 mm. The larva feeds in this stage. 



Stage II. — Tubercles absent, a single tiny seta represents each. 

 Subdorsal ridge rounded, prominent. Dorsum hollowed, sides perpen- 

 dicular. Skin obscurely granular, the granules flattened, nearly con- 

 tiguous, not really overlapping but suggesting scales, especially before 



