NOTES ON A DECAPOD CRUSTACEAN 
121 
situated along a broad angle and with its elevated edges gives su- 
perficially the appearance of a ridge. Anteriorly the groove has 
a low but well marked rim or edge on either side and these rims 
become more prominent and the groove less so until at the pos- 
terior end the two rims blend into a ridge or carina and the 
median groove becomes obsolete. (Figure 1, lc.) Extending 
from a point slightly anterior to the midlength of the dorsum 
and at right angles to it is a short shallow transverse gastric sul- 
cus; it reaches half way to the cardiaco-branchial groove or 
ridge and is deepest in the middle and decreases in depth to- 
wards both ends. Beginning at the anterior end of the cardiaco- 
branchial carina a broad rounded ridge extends poster o-dor sally 
past the ventral end of the transverse gastric sulcus to a dorso- 
median point immediately posterior to the midlength of the 
cephalo-thorax. This ridge or carina the writer will call the “cer- 
vical ridge” as opposed to the common cervical groove of mod- 
ern decapods. The portion of the cervical ridge between the 
transverse gastric sulcus and the dorsal end bears a fine mesial 
sinus. Running one millimeter dor sally and parallel to the an- 
terior portion of the cervical ridge from the hepatic sulcus to the 
transverse gastric sulcus there is a deep gastro-hepatic sulcus. 
Two millimeters from the ventral margin of the cephalo-thorax 
and beginning at the postero-ventral apex of the hepatic sulcus 
there is a strong marginal carina which tends, to coalesce with the 
free margin toward the posterior end. The entire free margin 
of the cephalo-thorax is slightly thickened and the ventral part 
of it bears a small sub-marginal groove. The portion of the 
branchiostegite from the marginal carina downward is inwardly 
inclined. 
The eye stalks are partly preserved. The one on the right side 
has a height of 5 mm. ; the left, 1 mm. A part of a laterally 
compressed peduncle of the right antennule is visible. The an- 
tennae are not shown but the proximal portions of well developed 
antennal scales are present forming a continuous shelf beneath 
the antennules, The line of demarcation has been obliterated 
but this condition may have been brought about by the process 
of substitution and by the great pressure exerted upon the thin 
inner margins of the scales which may have been partly imbri- 
cated at the time of entombment. Each scale has a prominent 
outer sub-marginal groove which probably represents the main 
