274 ZOOLOGY 



The head bears one pair of antennae, the first. Its second 

 joint bears a disk on which the duct of the cement gland opens. 

 In Lepas and Balanus this appendage is minute, and situated 

 at the base of attachment. The cement gland lies in the stalk 

 of the stalked forms, its secretion hardens into a cement which 

 serves to attach the animal to some foreign body. 



The second pair of antennae, although present in the larva, 

 are thrown off at the last moult, and are therefore not found in 

 the adult. Above the mouth is an upper lip or labrum, and 

 on each side of it is a mandible ; between the mandible and 

 the labrum is a structure called the palp, which, however, is 

 not the homologue of the ordinary Crustacean palp. There 

 are two pairs of maxillae, the posterior pair being fused together 

 to form a kind of labium. 



The thorax bears six pairs of appendages, the biramous 

 nature of which recalls the limbs of the Copepods (Fig. 163). 

 The rudimentary abdomen has no appendages, it terminates in 

 a long penis, which is usually bent forward between the thoracic 

 legs. 



The mouth leads by a short oesophagus into a globular 

 stomach provided with certain hepatic diverticula ; the intestine 

 passes off from the stomach and ends in a short rectum. The 

 anus is situated dorsally at the base of the penis. 



In addition to the hepatic diverticula certain glands have 

 been described lying near the stomach, with which they com- 

 municate by a duct on each side. These glands secrete a fluid 

 which has probably some digestive action, they have been 

 termed pancreatic glands, formerly they were described as 

 ovaries. 



The Cirrhipedia seem to be devoid of any special circulatory 

 apparatus. The space between the internal organs of the body 

 is largely filled up with connective tissue, but certain cavities 

 occur which seem to be lined by an endothelium, and which 

 have been regarded as truly coelomic. Into these spaces a pair 

 of ducts open by means of funnel-shaped orifices. These 

 ducts have been traced in one or two genera, and have been 

 found to open on to the exterior at the base of the second maxilla, 

 the appendage which bears the aperture of the Entomostracan 

 excretory organ, the shell gland. These tubes are believed to 



