1894,] TELEOSTBAJSr MORPHOLOGY. 431 



what was presumably its original relationship to the morpho- 

 logically ventral side of the eye. 



Dr. Griinther considered that the structure he described might 

 represent a saccus lacrymalis, but I do not see there is any reason 

 to regard the recessus of flat-fishes in that light. The saccus is 

 a superficial structure developed altogether outside the eye, never 

 acquiring any but a topographical (and physiological) relationship 

 therewith. It is always in intimate relationship with the laciymal 

 scute ; but no flat-fish with which T am acquainted possesses any- 

 thing that can be homologized with this scute, while such other 

 fishes as I have examined, which do exhibit structures to which 

 that name has been applied, show no trace o£ an accessory visual 

 organ. 



The lacrymal gland suggested itself to me at one time as a pos- 

 sible homologiie; but beyond a certain similarity of position, of 

 innei'vation, and of blood-supply, there is little evidence in favour 

 of this hypothesis either. The lacrymal gland arises in Mammalia 

 as a solid outgrowth of the conjunctival epithelium into the under- 

 lying connective tissue, subsequently becoming hollowed out to 

 form the cavities of the gland and ducts \ and never enters into 

 any relations \^ith the inner orbital cavity. Of the development 

 of the recessus I have no knowledge ; but if it is ever connected 

 with the conjunctival region, tlie position of the organ of the upper 

 orbit shows that this connection must be lost at a very early period 

 prior to the migration of the eye. If a gland at all, it is destitute 

 of glandular epithelium, or, at all events, I have failed to find 

 any. 



It is, of course, equally possible that a gland might in process 

 of evolution take on new functions and lose its glandular nature, 

 or that a non-glandular ancestral structure might become specialized 

 for a glandular function ; but, in the absence of any information 

 as to the origin of the lacrymal gland of higher animals, speculation 

 on this point is more or less idle. 



From what we have seen of the anatomy of the recessus in its 

 fuUy developed condition, it appears to me most reasonable to 

 regard it merely as a part of the ordinary membrai^ous wall of the 

 orbital cavity, specialized to perform certain definite functions in 

 connection with the elevation of the orbit, and not homologous 

 vidth any organ known to exist in the eye-apparatus of higher 

 animals, and I have been guided by this opinion in my choice of a 

 name. It may probably occur rather widely in Telosteans which 

 have the habit of burying themselves in the sand. Of such forms 

 I have only examined Trachinus draco and T. vijyera, in both cases 

 with negative results. 



In conclusion, my thanks are due to my friend and teacher, 

 Professor Howes, for many valuable suggestions. 



^ Cf. Kolliker, Entwick. des Mensch., Leipzig, 1879, p. 699. I am indebted 

 to my friend Mr. M. F. Woodward for this and other references beariug on 

 the same subject. 



