282 



LECTURE Xm. 



The marine animalcules brought to the mouth (Jig. 124, a), by the 

 currents of the cirrigerous feet {h\ and seized by the lateral jaws, are 



]24 



Lepas. 



conveyed by a short oesophagus, having a bell-shaped expansion of the 

 lining membrane, to a dilated stomach (c), which is of unusual length 

 in Tubicinella. From six to eight casca are developed from the upper 

 part of the stomach, in several species of Balanus, and are branched 

 in Bal. perforatus. They are not developed in Tubicinella. The 

 intestine {d) is bent upon the stomach, and tapers with a slightly 

 sinuous course to terminate at (d'), the base of the caudal appendage (e). 

 The intestinal canal is lined by a chitinous epithelial tube, which is 

 continued above into the caeca. Darwin has observed it to be ex- 

 pelled entire, with the excrement, in a living Balanus ; it has been 

 deemed analogous to the typhlosole in the earth-worm's intestine.* 



The stomach is coated by small, opaque, pulpy, branched glands, 

 probably subserving a hepatic function : these are arranged in longi- 

 tudinal lines in most Barnacles. 



Poll states that he saw a heart pulsating a little above the anus, 

 and Dr. Coldstream, who quotes the remark, says that there is a 

 "central canal situated on the dorsal aspect of the body;"f but the 

 exact condition of the circulating system of the Cirripeds has yet to 

 be determined, and by the examination of living specimens. Much 

 of it — probably all the venous part — appears to be in the condition 

 of diffused channels or sinuses, defined only by the extremely delicate 

 tunica propria of the veins. There is one main channel along the 

 ventral surface of the thorax, dividing and surrounding the mouth, 

 and giving out branches which enter the inner of the two channels 

 in each thoracic leg ; there are also two canals in the penis. " There 



* CCXV. p. 26. 



t CCXVI. p. 689. 



