224 HAROLD HEATH. 



Middendorff correctly describes the visceral artery which 

 springs from the head cavity and surrounding the radula sac 

 supplies the alimentary canal and liver. The blood passing from 

 the capillaries pours into the visceral cavity and joining that from 

 the foot, proboscis and gonad proceeds through the meshes of 

 the kidney to enter the lateral sinus. 



The lateral sinus in Cryptochiton is a relatively large canal sur- 

 rounded by connective tissue and muscle fibers in whose wide 

 meshes are vast numbers of " granulazellen." Anteriorily it 

 arises near the mid-line in the furrow surrounding the snout from 

 which it receives a few small vessels while numerous others of 

 large size drain the blood from the mantle. Coursing backward 

 and constantly increasing in size it continues to receive vessels 

 from the mantle and finally in the vicinity of the reproductive 

 opening it unites with the branchial artery. 



The accompanying diagram will serve to illustrate the course 

 taken by the blood in passing through the body, at least it repre- 

 sents the main canals. It will be seen that the well-developed 

 lateral sinus plays an important part, acting as a collector for 

 the blood from all parts of the body and possibly its surrounding 

 walls serve to remove certain wastes before being passed to the 

 branchial artery. 



The relations of the branchial artery and the branchial vein to 

 the gills and the connections of the latter vessel to the heart are 

 already well known and require no further comment. 



LITERATURE CITED. 

 Brock, J. 



'83 Untersuchungen iiber die interstitiellen Bindesubstanzen der Mollusken. Z. 

 wiss. Zool., Bd. 39. 



Haller, Bela. 



'82 Die Organisation der Chitonen der Adria. I. Theil, Arb. Zool., Inst. 

 Wien, Bd. 4. 



'83 Die Organisation der Chitonen der Adria. II. Theil, Ibid., Bd. 5. 

 Heath, Harold. 



'97 External features of young Cryptochiton. Proc. Acad. Nat.'Sci. Philadelphia. 



'99 The development of Ischnochiton. Zool. Jahrb., Bd. 12, Anat. 

 Middendorff, Th. 



'49 Beitrage zu einer Malacozoologica Rossica. Mem. Acad. St. Petersbourg 

 (6), Bd. 6. 



