THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[TfflRD SERIES.] 



•* per litora spargite museum, 



Naiades, et circiJm vitreos considite foiites : 

 Pollice virgineo teneros hlc carpite floras : 

 Floribus et pictum, divae, replete canistrum. 

 At vos, o Nymphae Craterides, ite sub undas j 

 Ite, recurvato variata corallia trunco 

 Vellite muscosis e rupibus, et mihi conchas 

 Ferte, Ueaepelagi, et pingui conchylia succo." 



N. Parthenii Giannettasii Eel. 1. 



No. 109. JANUARY 1867. 



I. — On the Organs of Circulation of the Roman Snail (Helix 

 pomatia). By Charles Robertson, Demonstrator and 

 Curator of the Anatomical Collection, Oxford. 



[Plate I.] 



The very imperfect account given in most of the standard works 

 on comparative anatomy of the organs of circulation of the 

 Gasteropoda has induced me, from time to time, to try various 

 experiments and injections for the purpose of determining the 

 course of the blood and the existence of a capillary system be- 

 tween the arteries and veins''^. 



The majority of recent writers agree in their accounts of the 

 vascular system, and describe the artery and its branches as far 

 as the head, where it is said to terminate in a sinus which sur- 

 rounds the nerve-collar, and this, again, communicates with other 

 sinuses in other parts of the body. These spaces left between 

 the artery and vein have been named lacunae, or intervisceral 

 spaces ; and the circulation is therefore said not to be closed 

 throughout its course, and the capillary system is generally 

 wanting. 



Milne-Edwards, in his elaborate and instructive paper on the 

 organs of circulation of the Mollusca, describes the arterial and 



* Owen's Lectures on Comparative Anatomy (1855), p. 559; Carpen- 

 ter's Comparative Anatomy (1854), p. 252; Siebold, Anatomy of the 

 Invertebrata, translated by W. L. Burnett (1854). 



Ann. §• Mag. N, Hist. Ser. 3. Vol. xix. 1 



