PHYSIOLOGY OF THE INVERTEBRATE HEART. 125 



pallial and pedal on the ground that they are physiological mis- 

 nomers, and such they are to some extent. The same objection 

 may be raised to the names "visceral ganglia" and "visceral 

 nerves " or " pleuro-visceral commissures," because these ganglia 

 innervate other structures besides the viscera and because some 

 of the visceral organs are innervated by nerves from other 

 ganglia. The stomato-gastric nervous complex of the cephalo- 

 pods and the gasteropods is as much " visceral ' as the two 

 pleuro-visceral connectives with their peripheral complex of 

 ganglia. This is recognized by Haller (1882), who calls the 

 buccal ganglia of the prosobranchs the " anterior visceral gan- 

 glia." But this requires new names for the visceral nerves in 

 the cephalopods and for the pleuro-visceral connectives in the 

 gasteropods. The principle of naming the different ganglia and 

 nerves with reference to the organs innervated by them is the 

 correct one, as it will insure the greatest possible uniformity of 

 names in the different groups. But our knowledge of the 

 molluscan nervous system does not yet allow such a revision of 

 the terminology. And for that reason I will make use of the 

 names visceral nerves and visceral ganglia, inadequate and mis- 

 leading as they are, rather than burden the literature with addi- 

 tional terms, which in all likelihood would prove to be but. 

 makeshifts. 



In the dissections no attempts have been made to work out the 

 innervation of other organs besides the heart, except in so far as 

 the nerves to the cardiac apparatus are involved. In the figures 

 the nerves to the various visceral and pallial organs are indicated 

 for the purpose of orientation. The results of the dissections by 

 aid of a good hand lens have not been supplemented by histo- 

 logical methods. Frequently nerves could be followed to the 

 base of the auricles or on to the aorta but not on to the auricles 

 and the ventricles themselves, although stimulation of the nerves 

 showed that the nerves entered these organs. I have no doubt 

 that in such cases the nerves could have been traced on to the 

 cardiac musculature by aid of histological methods. 



i . The LaincllibrancJis. - - Nerves to the cardiac apparatus of the 

 bivalve molluscs have been described by Quatrefages (1849) f r 

 Terredo, and by Hancock and Embleton (1852) for My a tnmcata. 



