478 



J. F. ILLINGWORTH, 



Explanation of Figures. 



The following abbreviations have been used: 



A anus 



Af afferent branchial sinus 



Ag glands of auricle (Keber's 



organ) 

 JBas basibranchial sinus 

 JB, s buccal sinus 

 Sue buccal ganglia 

 Sue. e buccal commissure 

 C. s cerebro-buccal connective 

 C.ep columnar epithelial cells 

 Car cerebral ganglia 

 Cer. e cerebral commissure 

 Col columellar muscles 

 C.p. e cerebro-pedal connective 

 Cp. Ch circumpallial chord 

 C.pl.e cerebro-pleural connective 

 Ct Ctenidia 

 Dg Digestive glands 

 Di diaphragm 

 E eye 



Ef efferent branchial sinus 

 E.n nerve to eye 

 Exr external opening right ne- 



phridium 

 F foot 



Gr genital organs or mass 

 Gas gastric nerve 

 Q.C ganglionic cells 

 G. d genital duct or oviduct 

 Gen. e genital cavity 

 G.g gill ganglia 

 H.d hepatic ducts 

 H.w nerves to head wall 

 In intestine 

 J jaws 

 E. nerves to right nephridium 



L labial nerves 



Lab. g labial ganglia 



Lat lateral pedal collectors 



L. i. p left internal palliai nerve 



Liv liver 



L.n left nephridium 



Lp lower palp 



M. e mantle cavity 



Med median pedal collectors 



Mf mantle fissure nerve 



Mo mouth 



Mn anterior mantle nerves 



Mp multipolar nerve cell of 

 osphradium 



N. C nerve from cerebral ganglion 

 to otocyst 



N.W nerves to neck wall 



place from which to inject vas- 

 cular system 



Oe oesophagus 



Oe.n nerve to sides of oesophagus 



Os osphradium 



Os.g osphradial ganglia 



Ot otocyst 



P. e pericardial cavity 



P. Ch pleural chord 



Ped. Che pedal chord 



Ped. Com pedal commissure 



Ph glandular pharynx 



Pm.n nerve to protractor muscles 



P.n jDedal nerve from cerebro- 

 pedal connective 



P. P. Con pallio-pleural connective 



P. P. n paired pedal nerves 



R rectum 



Ra reno-anal nerve 



