CRUSTACEA 



339 



on the ventral side. Within the mantle cavity lies the body, turned 

 over on its back with the appendages upwards (or downwards, as the 

 animal hangs) and connected with the peduncle and^mantle only at 

 the extreme anterior end, where there is an adductor muscle By which 



tgm. 



an'. 

 Fig. 244. A view of Lepas anatifera, cut open longitudinally to show the dis- 

 position of the organs. From Leuckart and Nitsche, partly after Claus. 

 stk. stalk; car. carina; tgm. tergum; scu. scutum; an.' antennule; md. man- 

 dible with "palp" in front; mx.' ist maxilla; mx." 2nd maxilla; Th. the six 

 pairs of biramous thoracic limbs; Ihr. labrum; M. mouth; oe. oesophagus; 

 Ir. "liver" coeca; st. stomach; An. anus; ov. ovary; od. oviduct; t. testes; 

 ves.sem, vesicula seminalis; p. penis; cetn. cement gland and duct; add. 

 adductor scutorum muscle, which closes the carapace ; mtl.ca. mantle cavity, 

 i.e. the space intervening between the carapace and the body. 



the sides {valves) of the mantle can be drawn together and so the 

 opening closed. The antennae^ which should be somewhere in this 

 region, are absent. The prominent mouth is overhung by a large 

 labrum. At its sides stand the mandibles ^ which have a flat, toothed 



22-2 



