1899.] BLOOD-TESSELS OP TELEOSTEAN FISHES. 947 



Mullus, Corvina, Equula, Zeus (fig. 22), Trachinu^. 

 Anarrhichas (fig. 23), Zoarces, Centronotus, Sphyrcena, 

 Lahrus (fig. 24), Hemiclwomis, Exoccetus (fig. 25). 

 Subgroup C. The third and fourth vessels unite, the 

 common stem sloping backwards towards the aorta. — 

 Lophius (fig. 26), C'o«Ms(fig. 27), Trigla (fig. 28), Cydo- 

 pteriis (fig. 29), Gobius, Ftsiularia (fig. 30), Lepado- 

 gaster, Saccohranchus (fig. 31), Silurus (fig. 32). 



Group D. The four efferent branchial vessels open into the 

 circulus cephalicus. 



Subgroup a. The third and fourth vessels open separately. 



— SyngnaOms (fig. 33), Motella. 

 Subgroup b. The third and fourth vessels open together. — 



GciHtrosteus, Garhcs (fig. 34), Molva, Hippocampus. 

 Subgroup c. The third and fourth vessels unite before 



joining the circulus cephalicus. — Blennius (fig. 35), 



Orthagoriscus (fig. 36), Tetrodon (fig. 37). 



Special Paet. 



In the case of species not figured, comparisons wnll be drawn 

 with those figured forms which, in the arrangement of the efferent 

 branchial vessels, they most nearly resemble, irrespective of the 

 degree of atfinity which upon other grounds may be considered to 

 exist between the forms. 



FUETHEE EeMARKS ON GeOUP A. 



In Eiigraulis (fig. 1), there is a considerable difference in the 

 size of the four efferent branchial vessels ; the second is the 

 broadest, and the first the narrowest. The dorsal aorta behind 

 the fourth branchial vessel is wide and very thin-walled. This is 

 also the case in Clujjea. Although the scheme of classification 

 which it has been found convenient to adopt brings Ammodytes 

 (fig. 3) under the same subgroup as Clupea (fig. 2), there are 

 several features which go to show that the association is an 

 unnatural one. The circulus cephalicus in the former genus is 

 much longer than broad, and extends back nearly to the point of 

 entry of the second pair of vessels into the aorta ; whereas in 

 Clupea the posterior part of the circulus is transverse to the axis 

 of the body, and forms with the first part of the aorta a T rather 

 than a Y. The coeliaco-mesenteric artery arises in Ammodytes 

 close behind the fourth efferent vessels, but much further back in 

 Clupea. The origin of the subclavian arteries is slightly more 

 posterior in Clupea than in Ammodytes. There are no differences 

 between Ammodytes lanceolatus and A. tohianus, nor between 

 Clupea harengus and C. sprattvs. 



Chirocentrus closely resembles Megalops (fig. 4). In both 

 genera the median aortic stem found in EngrauJis and Clupea 



