1906. J ANATOMY OF CENTROPHORUS CALCEUS. 875 



point out that the attachments of the slightly larger spleen con- 

 clusively prove what I have stated above, namely, that the j)ylorie 

 portion of the stomach does not normally lie in apposition with 

 the cardiac, but includes a large angle wil3h it. 



The pancreas is peculiar in form and is situated, in attachment 

 with both the bile-duct band and the duodenum, just anteriorly 

 to the commencement of the spiral-valve intestine. It consists 

 of three elongated lobes disposed as shown in PL LVII. fig. 3. 

 Fig. 3 a represents the reverse aspect of the gland. The pan- 

 creatic duct opens into the large intestine at the commencement 

 of the latter where the lobe of the pancreas attached to the 

 duodenum is in contact with it. The internal aperture is not 

 very conspicuous and lies close to the first fold of the spiral 

 valve. 



The rectal gland (PI. LVII. fig. 1) is in shape much like that 

 found in the Common Dogfish, and is similarly supplied with the 

 posterior mesenteric artery. 



I have yet to mention that on opening the body-cavity of the 

 fish, I foimd a large yellow- mass of (apparently glandular) tissue 

 overlying the extreme anterior end of the cardiac portion of the 

 stomach and abutting against the posterior wall of the peri- 

 cardium. I am unable to give any opinion as to the nature of 

 this mass, since I have not yet had an opportunity of examining* 

 it histologically. 



I have examined a specimen of Centro-phorus calceus in the 

 British Museum, ond, so far as I could ascertain, the visceral 

 anatomy was identical with that of my own specimen. 



Remarks on the Vascular System. 



The heart of C. calceus is of the ordinary selachian type,, 

 consisting of a large transversely-elongated sinus venosus, thick- 

 walled venti'icle, and capacious atrium or auricle. The internal 

 wall of the ventricle is spongy in nature owing to the presence of 

 muscular fibres, and to a less extent the wall of the atrium 

 is similarly characterised. A. pair of atrio-ventricular valves is 

 as usual present at the atrio-ventricular passage. The conus 

 arteriosus is somewhat longer than the ventricle, and possesses 

 only tAVO transverse rows of valves in its cavity : one, consisting 

 of three pocket-shaped valves, at its origin from the ventricle, 

 and the other situated at about one-third of the length of the conus 

 from the commencement of the ventral aorta and also consisting 

 of three valves. It is diflicult definitely to compare the number 

 of valves present in the conus of C. calceus with the number 

 found in other Selachians owing to the fact that different authors 

 often assign different numbers to the same species (to some extent 

 due to variation in the specimens themselves, pei'haps also to 

 a confusion between transverse and longitudinal rows) ; but 

 despite this, it is certain that the existence of only two transverse 

 tiers of valves in C. calceus distinguishes this species from other 



