170 ALLEN 



What is designated as the cephalic sinus in Sco?'pceiiichthys 

 (Figs. 4 and 5, Cefih.S.) does not fit very well into any of these 

 classes and seems to constitute one of its own. Here this sinus 

 is a sort of stomach-shaped reservoir situated between the 

 hyomandibular bone and the first internal branchial levator mus- 

 cle, which would make it nearly opposite and a little below the 

 level of the cerebrum and the optic lobes. Its cephalic dorsal 

 corner gradually tapers down into a papilla, which passes in- 

 ward and empties into the jugular directly behind the prootic 

 process. At this point the jugular itself expands into a sort of 

 reservoir before greatly diminishing in caliber to pass through 

 the foramen formed by the prootic bone and its process. In a 

 large uninjected specimen of Ophiodon from which a portion 

 of the dorsal wall of the jugular had been removed the orifice 

 could be distinctly seen from the inside of the vein. It pierced 

 the ventro-lateral wall a little behind the prootic process, and 

 was guarded by a strong valve that opened into the vein. This 

 valve was attached dorsad, but was free three fourths of the 

 way around. As the cephalic sinus papilla passed behind the 

 prootic process to empty into the jugular it recieves the super- 

 ficial facial trunk. In the posterior ventral corner of the cephalic 

 sinus there is a second opening into which a prolongation of the 

 hyoidean sinus enters. A third opening remains to be noted in the 

 posterior dorsal corner, which is in connection with a lateral 

 papilla from a sinus at the cephalic end of the cranial lymphatic 

 trunk (Figs. 4 and 5, S). As previously stated this sinus corres- 

 ponds in position to the cephalic sinus described and figured by 

 Hyrtl in Leuciscus, however, in Scorjicenichthys this sinus does 

 not empty directly into the venous system ; anteriorly it tapers 

 rapidly down into a papilla that passes ventrad between the 

 cephalic sinus papilla and the first internal branchial levator 

 muscle to communicate with the cephalic end of the abdominal 

 sinus, but in no case was any direct connection noticed between 

 it and the cephalic sinus, the cephalic sinus papilla, or the jug- 

 ular vein. As stated above the connection of this sinus with the 

 cephalic sinus comes from its lateral wall. Sinus S in Scorfce- 

 nichthys (Figs. 4 and 5) is therefore to be regarded as simply an 



