Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 171 



evident that the branches that innervate the organs in the two fishes 

 must also be homologous. This I have already had occasion to 

 refer to (No. 8), and it will be further discussed in describing the 

 nerves. In Polyp terns the arrangement, as deduced from Pol- 

 lard's descriptions (No. 58, p. 397), is apparently the same as it is 

 in Amia, excepting that the squamosal of Polyptcrns is fused with 

 the parietal. In Menidia the first organ posterior to the preoper- 

 culo-mandibular canal is, according to Herrick (No. 36), inner- 

 vated in the same way as the posterior squamosal organ of Scom- 

 ber is, but whether this organ, in Menidia, lies in the squamosal 

 or not is not stated. In the cod Cole (No. 16) says this organ is 

 absent, but, as already stated in an earlier work (No. 8), it may 

 be found to be represented in the organ called by him organ No. 

 3 of the lateralis canal. 



The first twelve organs of the line in Scomber are separated, by 

 their innervation, into three groups. The first group contains the 

 first five organs of the line, four of which lie in the lachrymal and 

 one in the suborbital bone. The second group contains the four 

 organs that lie in the bones of the postorbital series. The third 

 group contains the one organ that lies in the postfrontal and two 

 of those that lie in the squamosal. The organs of the first two 

 groups are innervated by branches of the buccalis facialis ; the 

 organs of the third group by branches of the oticus facialis. 



Between the first and second grovips of organs the main canal 

 changes abruptly in direction, and the anterior organs of each 

 group lie much closer to each other than the posterior ones. This 

 is readily seen in the disposition of the dendritic systems, and, 

 taken together with the manner of innervation, seems to indicate 

 some independence in the development of the two parts of the 

 canal. A similar independence of development was indicated by 

 a similar grouping and innervation of the organs in Amia (No. 2, 

 p. 514), but there was, in Amia, another group of infraorbital 

 organs lying anterior to those found in Scomber. These anterior 

 organs in Amia were four in number, on each side of the head, 

 and formed the anterior cross commissure of the lateral system. 

 Two of the organs lay in the antorbital bone and two in the cor- 

 responding half of the median ethmoid bone. Two of these 

 organs, and possibly also the bone that encloses them, are appa- 



