Report of rut: State Geologist, 



513 



As observed by < Khlert, 



genital glands are in direct connection with the blood ; am 



the body-walls, the oviducts and the 



the 



intestine, the muscles and the Liver are enveloped by membranes 



st) delicate that they can not obstrucl the action of the nourishing 



fluid." 



Respiration. 



The function of respiration has no special organ or set of 

 organs for its perf prmance ; it is not localized, but is evidently 



effected wherever the tenuous tissue of the animal with its circu- 

 latory vessels is exposed to the oxygenated water. The mantle 

 is principally concerned in this function, and the long spiral 



Fig. Y3&.— Magellania flavescens; showing the 

 brachial (Davidson.) 



Fig. 139. — Extremity of the arm of 

 Crania. (Joubin.) 



brachia undoubtedly contribute, though perhaps not to the extent 

 attributed to them by some authors, who have compared them 

 to, and regarded them as branchiae or gills. 



The water entering the brachial chamber of the shells is con- 

 stantly renewed by the opening and shutting of the valves, and 

 perhaps more effectively by the constant play of the cilia with 

 which the outer edges of the arms are fringed. 



In this place a brief account of these arms, their variations 

 in form and the nature of their calcified supports will be given. 



Brachia. The brachia are labial appendages taking their 

 origin about the oral opening and extending in various graceful 

 1891. 65 65 



