346 NEW YORK STATE MUSEUM 
another characteristic set of striae is added posteriorly of the frontal set. 
The second set consists of curving striae running obliquely backward and 
inward from the antelateral angles and lateral margins [pl. 66, fig. 10] and 
connected by anastomosis with the frontal parallel line. Along the lateral 
margins they are dissolved into a meshwork of lines. Like systems of lines 
appear on the metastoma, where they pass transversely across, with a slight 
forward convexity, and on the coxa where they strongly anastomose. The. 
coxal segments and the metastoma were also furnished with a fine striation. 
Ontogeny. The ontogeny of H. shawangunk is well shown in 
the small series of individuals reproduced on plate 64: The most interest- 
ing of these specimens is the original of figure 1 which is but 2 mm long and 
very distinct. This larval form is a clear representative of the nepionic 
growth stage. It still lacks two, possibly three, segments of the full 
complement of twelve. Its most important feature is the remarkable 
general similarity to the mature stage of the species, in the slenderness and 
form of body, form of carapace and eyes and position of the latter. Its 
most distinctive larval characters are (1) the relatively greater size of the 
carapace, (2) the relatively great size of the compound eyes, (3) the smaller 
number of segments. 
The carapace in the nepionic stage attains one fourth the length 
of the body, while in the ephebic stage it reaches only one fifth. The head 
is also broader than the rest of the body while in the mature specimens 
the greatest width is reached in the middle part of the preabdomen. It 
also seems that in this and the following growth stages the head is relatively 
somewhat shorter in outline than in mature forms (by about one eighth 
of the width) and slightly more rounded in front. 
The compound eyes do not differ in location from those of the mature 
individuals, being intramarginal and separated by a small interval from 
the margin, but they are markedly larger, occupying one half the length 
of the carapace as compared with one fourth to one fifth in the mature 
stage. They are likewise distinctly more prominent; at least in the spec- 
imens representing the neanic stage. 
