SECEETORT SACS IN TELEOSTEI. 545 



Jordan * describes an accessory branch of the lateral line as 

 passing backward from the head along the back o£ the dorsal 

 fin. It is connected with other peculiarities, and must have 

 some relation to the mode of life of the different species ; and 

 in the case of Cynoglossus it is present along v\ith certain 

 characters which plainly show the greater adaptation of it.s 

 possessor to more sand-loving habits than those which do not 

 have it. 



In the case of Solea, it has been said that one of the nasal sacs 

 extends backward over the roof of the mouth, whilst the other 

 is quite separate and lies anterior to the ethmoid. In the four 

 specimens of Ci/noglossus, so far as could be ascertained by 

 means of a seeker without actual dissection, there is a single 

 large sac lying over the roof of the mouth, resembling in position 

 the large posteriorly directed sac of Solea. Into this both nasal 

 canals open — one from each nasal cavity. The nasal org.ins, 

 which are placed symmetrically on each side of the head, are thus 

 in communication with a large "cul-de-sac" which occupies the 

 entire area overlying the median portion of the roof of the mouth. 



The step is not great from this combination to that found in 

 the divergent specimen. The roof of the mouth in this is 

 perforated by a large oval opening (PI. 38. figs. 3, 4, 5, c), around 

 which the mucous membrane is thrown into a broad rim or fold, 

 projecting inward and underlying a portion of the central 

 chamber, which in position corresponds to that enclosed by the 

 sac of the other four specimens. "When this rim is cut throut^di 

 anteriorly, two comparatively large openings are seen (tig. 5) 

 — one on each side of the median line. These lead into 

 the nasal canals which pass upwards and forwards — one on 

 each side of tlie parasphenoid — internal to the palatines, until 

 they reach positions anterior to and alongside of the ethmoid, 

 and open at their upper extremity into the posterior portion of 

 the nasal cavities (fig. 3, e). On the eyed side of the head the 

 canal passes downward from the nasal cavity close to the 

 membranous lining of the lower orbit (fig. 3, n.p.c). These 

 canals are tolerably large, and form an effective means of 

 communication from the exterior, through the nasal cavities 

 to the mouth. 



* Jordan, D. S., & Goss, D. K. : "A Eeview of the Flounders and Soles 

 (Pleuroneetidse)," Rep. U.S. Oomm. of Fish and Fisheries, 1886.— Jordan, D. S. 

 & Evermann, B. W. : ' The Fishes of Noith and Middle America,' 1898. 



