ce 



N IN KTEl'A'TH R E PORT. 



one runs along the upper lialf of the fin for about two-thirds of Its 

 length, nearly midway between the border of tlie fin and the myotomes. 

 The second extends back, following the centre of the myotome region, 

 nearly to the tip of the tail. A pair of sliort rows are located dorso- 

 laterally on either side of the liead. They run backward, one row of 

 each pair passing on either side of tlie nares and the eye. Behind the 

 eye, the organs are rather irregularly' arranged, although one or more 

 short definite rows may occur. The anterior lateral surface bears other 

 rows of sense organs, as shown in the diagram, (Fig. 1.).. The distribu- 

 tion of tlie lateral lines is practically identical with that in Rana 

 catesbeaua. as described by Kingsbury-. 



Structure. As regards structure, these sense organs, when seen in 

 vertical section under tlie microscope, closely resemble taste buds. They 

 are composed of a cluster of somewhat conical cells radiating from a 

 more or less pronounced pit or crater in the outer surface of the skin. 

 The cluster usually extends the full depth of the epidermis. Kingsbury 

 recognizes two kinds of cells, a few shorter inner cells, surrounded 



Figure 2. Cross-section of epidtiinis from tadpole of Rana clamitan.t, showing 

 structure of a lateral line organ. 



by several longer, slenderer ones. Fig. 2 shows two nuclei separated 

 from the others, and lying nearer the surface, which probably represent 

 the nuclei of the inner and shorter cells. The nuclei of the cells com- 

 posing the sense organs are situated at the inn;>r end of the cells, and the 

 cytoplasm is relatively clear. The structures are, in general, similar to 

 tliose figured by Kingsbury for the larvae of Aniblystoma. and several 

 other Urodeles, excei)t that in the case of Rana clamitans, the cells com- 

 ))rising the sense organ are shorter and less lunnerous. 



LITERATURK. 



Dickcrson. Mary I',. li)()7. The Frog Hook. p. (i. 



Kingsbury, B. I". l.SJtj. The Lateral line system of Sense Organs in 

 some American Amphibia, and Comparison with Di))noans. Proceedings 

 of the American .Microsco))ical Society, \'(tl. 17. pp. il.")-!.")!. 



Wright. A. 11. I!)ll. North .Vincricni -Vniira. 



