604 CLASS X. 



insects. In Oniscus and Porabea, according to TREVIRANUS, four 

 short vessels, which open into the rectum close to its extremity, 

 may perhaps correspond to the urinary vessels, or, as he supposes, 

 to the biliary, although they differ from them greatly by their 

 shortness 1 . As little are salivary organs known hitherto, except 

 in the Cirripedia. The liver, on" the contrary, is commonly much 

 developed here. In some lower crustaceans the intestinal canal is 

 surrounded by a layer of small blind sacs (folliculi) or glandules, 

 which may be regarded as a liver intimately connected with the 

 intestine. In the Cirripedia the intestine below the stomach is 

 surrounded by a liver formed of many blind sacs. In the Oniscides 

 from two to six long blind liver-tubes are found, in most of the 

 genera four, often with dilations like a string of beads, which are 

 described by some writers as the adipose body of these animals. 

 In Bopyrus the intestinal canal, according to RATHKE, receives 

 seven liver-tubes on each side, which lie behind each other in the 

 length, an arrangement which recalls that in the scorpions, whilst 

 besides an unpaired liver-mass, incised into three parts, lies in front 

 of the others on the stomach 2 . In Limulus there are two very wide 

 gall-ducts on each side, at some distance behind the pylorus / they 

 receive the blind convoluted tubes, of which the large liver-mass of 

 this animal consists. In the decapod crustaceans only one gall- 

 duct is found on each side, terminating in the intestinal canal, be- 

 hind the lower orifice of the stomach. The liver is a double and 

 symmetrical organ, as in most crustaceans, and each liver is divided 

 more or less distinctly into three lobes ; in each of these lobes runs 

 a tube, that terminates in the common gall-duct, and round about 

 the tubes blind sacs (folliculi) are set, which unite as fingers do. 

 These follicles consist of three membranes, of which the internal 

 and external present no special structure ; the external is more con- 

 sistent and more intimately connected with the middle membrane. 



1 Verm. Schr. i. s. 58, Taf. vn. fig. 38, i. g. 



2 In Squilla the liver consists of lateral blind sacs divided into branches that 

 extend throughout the whole intestinal canal, a disposition which agrees with that in 

 Bopyrus, and may also be compared with that in Aphrodita (see above, p. 211). 

 Above the liver, on the dorsal surface, lie the testes or ovaria, which also extend longi- 

 tudinally, and consist of branched glandular lobes. The ovaria of Squilla were de- 

 scribed by CUVIER as liver. See DUVERNOY Ann. <ks Sc. /., 2e Se'rie, Tom. vi. 

 1836, pp. 247251. 



