CRUSTACEANS. 603 
then curves into the stomach, which is placed almost perpendicu- 
larly. The stomach is compressed laterally, has thick muscular 
walls, and is armed internally with many oblong rows of horny 
spines. The pylorus projects conically into the intestine, which 
then proceeds horizontally backwards, lying in the first part of its 
course close upon the cesophagus that runs in the opposite direction, 
and lies below it!. In Sguilla the stomach is small, muscular, 
triangular, armed in its posterior or pyloric portion with horny, 
pointed spines. In the ten-footed crustaceans the cesophagus mounts 
almost directly upwards. The stomach is capacious, and in its first 
part entirely membranous. The uppermost and hindmost or pyloric 
portion of the stomach is supported by hard parts, and therefore, 
even in the empty state, remains expanded. To these hard parts 
teeth are attached internally, by the assistance of which the food is 
comminuted. The epithelium of the stomach, moreover, is covered 
with numerous prolongations or colourless hairs, invisible to the 
naked eye, whose points are directed backwards’. To this stomach 
different muscles are attached, which arise on the inside of the 
cephalothorax, and which can also work upon the teeth described 
above. These muscles are, beyond doubt, subject to the will of 
the animal, and consequently we have here the rare example of an 
organ of vegetative life that is moved by muscles of animal life. 
In some ten-footed crustaceans one or more blind appendages to 
the intestinal canal are observed, which probably are secreting 
organs’. There are some species in which two such blind tubes 
terminate in the intestine close to the inferior opening of the stomach, 
whilst a single third tube is attached to the intestine lower down. 
It is, however, this last unpaired tube which alone occurs in most. 
Unless this tube be regarded as an organ for the secretion of 
urine, no parts are known which correspond to the vasa urinaria of 
1 Recherches sur U Hist. nat. ec VAnat. des Limules, p. 17, Pl. 1. fig. 1 ¢, figs. 2—4. 
2 At the hindmost part of the stomach, behind and under the above-mentioned 
teeth, these hairs may be distinguished even with the naked eye. The stomach of the 
cray-fish has been often described and figured. We content ourselves with referring to 
the latest investigations alone, those of F. OESTERLEN, in MUELLER’s Archiv, 1840, 
s. 387—441, Taf. XII. 
3 See DuvERNOY in the second edition of Cuvier Leg. d’Anat. comp. Vv. pp. 228, 
229. In as far as they open close to the pylorus these blind appendages may perhaps 
be compared with the pancreas ; but ordinarily they are inserted further backwards. 
