The anatomy of a pteropod, Corolla (Cymbuliopsis) spectabilis Dall. 71 



Circulatory and Excretory Systems. 



As was mentioned earlier in the account tlie heart and kidney 

 are situated on the dorsal side of the visceral mass. Their more 

 exact relations are indicated in Fig. 11. From this drawing it will 

 be seen that the pericardium, roughly conical in shape, is relatively 

 spacious and contains not only the heart but a considerable portion 

 of the aortae. In living specimens the ventricle is doubtless relatively 

 more spacious and it is possible that the canal entering the heart 

 may also, when turgid, assume relatively large proportions. 



The blood entering the heart appears to come chiefly and per- 

 haps entirely from the kidney. In preserved material the vessels as 

 they leave the kidney tissue are extremely delicate and the canal into 

 which they unite is also relatively small and almost invisible. This 

 vessel passes directly to the ventricle and may be considered to re- 

 present the auricle but there is little save position that differentiates 

 it as such. The opening into the ventricle is an elongated slit and 

 though possibly guarded by valves none have been detected. 



The vessel leaving the ventricle divides immediately into two 

 branches. The posterior one passes at once into the tissue of the 

 liver where it breaks up into an extensive system of sinuses that 

 doubtless extend to other parts of the visceral mass. The anterior 

 vessel courses forward, and bending over to the right, extends around 

 the visceral mass to the mid ventral line. Here in the region of the 

 central , nervous system it breaks up into two branches each one of 

 which extends outward into the tissue of the fin. As the figures 

 show these main arteries branch repeatedly as they proceed but a 

 considerable distance from the margin of the foot they lose their walls 

 and pass into a system of exceedingly delicate sinuses whose exact 

 course has never been followed owing to the yielding nature of the 

 surrounding tissue that prevents the use of any injection mass. 



The kidney, as the figure shows, is a sac, semi-lunar in shape, 

 that is closely applied to the posterior wall of the pericardium. The 

 right side is usually more spacious than the left and appears to be 

 more largely composed of connective tissue and muscle fibres; while 

 the walls of the left half are thicker, more glandular and are more 

 bounteously supplied with blood sinuses that originate from the main 

 kidney sinus situated at the junction of the nephridium and visceral 

 mass (Fig. 12 s). The cavity of the kidney into which the products 

 are poured varies greatly in size in different individuals, in some 



