CIRRIPED1A. 421 



regarded as branchial, and in Conchoderma a similar process is 

 found at the base of each of the other thoracic feet. A fold of 

 the inner lining of the mantle projecting backward on either 

 side of the attachment of the prosoma to the carapace is the 

 " ovigerous frenum " of the Lepadidae, and it is apparently a 

 homologous structure, though no longer ovigerous, which is 

 converted into a respiratory organ in the Operculata (Darwin) 

 The tubular oesophagus extends forward from the mouth to 

 open into the dilated stomach, the walls of which are prolonged 

 into hepatic diverticula. Bending with the curvature of the body 

 the alimentary canal narrows into the intestine which runs 

 back, in some cases with a clearly defined rectum, to open between 

 the rudimentary abdomen and the base of the penis. In 

 Alcippe it ends blindly. 



Nervous system. A paired supra-oesophageal ganglion is 

 present, and in the Lepadidae a ventral chain of five ganglia. 

 In the Balanidae these latter are represented by a single large 

 ganglion. 



A vestige of the unpaired eye of the larva persists. 

 A heart appears to be absent. 



The excretory organs are represented, as usual in Entomostraca, 

 by the maxillary glands. Hoek described wide paired spaces, 

 with definite walls, leading to apertures in the second maxillae. 

 But it has recently been shown by Bruntz * that there are 

 in addition glandular sacks (simple in Balanus, divided into 

 alveoli in Lepas) lined by an excretory epithelium and opening 

 into the spaces of Hoek, which are in fact their dilated ducts. 

 Similar spaces are described by Berndt in Alcippe, but they 

 are said to be closed. 



Generative organs. In relation probably with their fixed 

 habit the Cirripedes are almost exceptional among Crustacea in 

 the fact that they are in the majority of cases hermaphrodite. 

 The testes (Fig. 273, T) are branched, glandular tubes lying at 

 the sides of the alimentary canal and extending into the bases 

 of the thoracic appendages. The vasa defer entia, after dilating 

 at their commencement to form vesiculae seminales, run back 

 to unite at the base of the long penis, which is traversed by 

 the common duct. The spermatozoa have a rounded head and 



* Contrib. a 1'etude de 1'excretion chez les Arthropodes. Arch, de 

 Biol. T. xx (1904) p. 219. 



