132 Invertebrate zoology. 



are thus opened and the organs exposed for study. The specimen should be 

 pinned down in a dissecting pan, the cut edges of the body wall drawn apart, 

 and the separate systems stiidied. The parts are to be identified by the synop- 

 sis given below, the details of form and relationship are to be left to the stu- 

 dent. It is well to notice the following points : The (dimentary canal may 

 be isolated first, following the windings of the intestine to the apex of the 

 spirals and back to the respiratory chamber. The large brown organ filling 

 the spirals is the Iwer, and should be removed with the canal. Take great 

 care and not harm the hermaphroditic gland, or its duct, lying in close con- 

 nection with the liver and intestine near the apex. Observe the central 

 ganglia of the nervous system lying upon the pharynx, and do not investi- 

 gate the interior of the pharynx until the nervous system has been stiidied. 

 When this is done, remove the pharynx for detailed study. Find the maxilla. 

 and the radula, a tough membrane covered with countless minute teeth, in 

 the interior of the pharyngeal cavity. This should be removed and mounted 

 in Balsam. 



I 05. A)iato)iiical Synopsis. 



1. Digestive system. Pharynx, an oval organ with very muscular walls, 



in which lie the maxilla and the radala — Short oesophagus expand- 

 ing into the large fiisiform stomach — Salivary glands, lying on each 

 side of the stomach, with long ducts, which open into the pharynx — 

 Intestine, which shows an enlarged area where the ducts of the liver 

 enter — Liver, several large dark-brown lobes, closely packed in the 

 upper part of the spiral — Anus, in the wall of the respiratory cham- 

 ber, close to the pneumostome. 



2. Reproductive system. Herniaphroditic gland and duct at apex of sac 



albuminous gland, a large white mass with a free end — uterus or 

 oviduct, a somewhat coiled crenate tube, accompanied on one side 

 by a smaller tube, the vas deferens — This latter leaves the ovidiTct, 

 makes a turn upon itself and expands into a sheath which contains 

 the penis or organ of copulation. The sheath opens at the genital 

 orifice — Theflagellum, a gland in the form of a long free tube at the 

 inner end of the penis-sheath — At end of oviduct a sac and two 

 bunches of finger-like glands. The sac contains a spicule which aids 

 in copulation, the so-called " Ciipid's arrow" (Liebesi^feil) ; the glands 

 probably assist in the formation of the egg-shell — The sjn'rmatheca, 

 a spherical sac, communicating by a long slender duct with the 

 lower portion of the oviduct. 



