2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 9I 



P. Bleeker "^ described and figured the peculiar bonelike supports of 

 the upper lip in Uroconger Icpturns (Richardson), and in a recent 

 paper P. J. Schmidt " describes and figures the labial elements and 

 throws further light upon their structure and function. Schmidt erred 

 in his structural description of these bony rays in denying their con- 

 nection or articulation with other bones of the head, stating that they 

 were free elements of the lip and not connected with any facial bones. 

 This author also refers to the porelike slits in the lip as pocketlike 

 invaginations between the labial bones, which facilitate the stretching 

 out of the membrane, and says they are not muciferous pores as was 

 generally supposed. 



Examination of the congrid material in the National Museum re- 

 veals the presence of these labial elements in various degrees of devel- 

 opment throughout the entire group of congrids. The bones are pres- 

 ent and can be detected with the aid of a pointed instrument in genera 

 with a free superior margin to the upper lip (example Ariosoma), 

 though the development is comparatively rudimentary in eels of this 

 type. In Uroconger lepturus the bony rays reach their peak of devel- 

 opment and are useful as distendable supports of the labial membrane. 

 Partial dissection of a paratype of one of the new forms reveals a 

 longitudinal bony muciferous canal extending from near the base of 

 the anterior nostril, laterally just above the lip, to the posterior border 

 of the orbital rim, where it bends upward following the curvature of 

 the eye. The interior, superior, and inferior walls of the tube are bony. 

 The exterior is open the entire length and covered only by the skin. 

 There are three small processes along the inferior flange of the tube 

 projecting into the labial membrane and appearing as minute sub- 

 dermal points on the oral edge of the lip. Examination of U. lepturus 

 reveals the same basic principle of development of the labial bones. In 

 genera in which the upper lip is without a free superior margin (ex- 

 ample Congr'ma) the labial bones reach the extreme margin of the 

 lip and in some instances project prominently beyond the margin. 

 The muciferous pores of the lip in this type of eel communicate with 

 the facial muciferous canal by very short tubes, it being possible to 

 insert a bristle in one slit and extract it from another. The writer, in 

 one of his new forms, inserted a bristle in the anterior pore and passed 

 it along the tube to a point opposite the posterior border of the eye, 

 showing that these slitlike openings are vents of the muciferous chan- 

 nel and not pocketlike pits for facilitating expansion of the labial 

 membrane, as contended by Schmidt. 



^ Atlas Ichth. Ind. Need., vol. 4. p. 20. pi. 149. fie. i. 1864. 

 ° C.R. Acad. Sci. U.R.S.S., 1929, pp. 189-193. figs. a-d. 



