876 MR. W. WOODLAND ON THE [Nov. 27, 



species of the same genus and from most if not all other genera 

 of the Squaliclfe. According to Giinther ", "the valves of the 

 conns arteriosus of the heart " in C squamulosus (and C. granu- 

 losus) " are ai-ranged in five transverse series, each series consisting 

 of three powerful valves and as many intermediate small ones"*. 

 According to Stolir"", the conus of Acanthias vulgaris 'possesaes 

 four rows of valves, but three according to Miiller ^* ; in Echino- 

 rhinus spinosits, three rows according to Tui-ner ", four according 

 to Jackson & Clarke "" ; in Lcemargus borealis, four according to 

 Turner " ; in Squalus maximus, four according to Home '^^ ; in 

 Squalus catulus, two according to Stohr. 



The afferent arches (PI. LVIII. fig. 4) are similar in construction 

 to those of the Common Dogfish: the "first" (first and second) 

 dividing into two at some distance from the median line to 

 supply the first two gill-clefts, the third arising from the 

 ventral aorta nearly an inch below the first and supplying the 

 third gill-cleft, and the "fourth" (fourth and fifth) arising just 

 behind the third and emulating the " first " arch by dividing 

 into two shortly after ; these respectively supplying the fourth 

 and fifth branchial clefts, and in this respect differing somewhat 

 fi'om Scyllnmn canicula. The afferent arches are the same 

 in C. granulostis ^'', save that the fifth afferent arches oi-iginate 

 from the main ventral aorta, as in the Dogfish. 



The efferent arches have the disjDosition shown in fig. 5. 

 The fourth pair arises about half-an-inch in front of the 

 coeliac artery, and by bifurca,ting in the usual manner sujDplies 

 the fourth and fifth gill-clefts. The third and second have the 

 same coirstruction. Between the third and fourth arches the 

 subclavian ai'teries arise. The first efferent arch forks over 

 the first gill-cleft, and fi'om the inner side of the fork gives off" 

 the common carotid which proceeds anteriorly and towards the 

 median line until it meets its fellow of the opposite side and 

 thence proceeds through the cartilaginous floor of the cranium 

 to the brain. About a quarter of aii inch from the junction of 

 the two carotids, each gives off an external carotid (the portion 

 of the carotid continuing towards the median line being termed 

 the internal carotid) which I'uns through the cai;tilage to the 

 inner wall of the orbit, where it divides into both anterior and 

 posterior branches as shown in PI. LXI. figs. 16 & 17. The first 

 efferent arches also give off", about half-au-inch from their origin, 

 two small vessels which run forwai'd for a short distance 

 pai-allel to the vertebral column, and wdiich possibly represent 

 the primitive paired condition of the aorta . There is no hyoidean 

 artery arising from the first efferent arch, such as exists in the 

 Common Dogfish. 



* Accorcliiifr to both Miiller and Owen, the presence oifour tiers of valves in theconus 

 is characteristic of the genus Centrophorus — an obvious misstatement of the facts. 



22 " Ueber den Klappenapparat im Conus arteriosus der Selachier und Ganoiden." 

 Morph. Jahrb. Bd. ii. 1876. 



23 " An Anatomical Account of the Sqiialits maxlmus, &c." Phil. Trans, vol. xcix 

 1809. 



