No. 2. — On the Lateral Canal System of the Selachia and 

 Holocephala. By Samuel Garman. 



Soon after his return from the Hassler Expedition, in 1872, Professor 

 L. Agassiz placed before me, his pupil at the time, a specimen of one 

 of the Batoidei, with the remark, " See what you can find out about it." 

 A preparation of the lateral line system was one of the results. This 

 was followed, under Professor Agassiz's directions, by other preparations 

 of the same system, which, one after another, were handed over to the 

 artist of the Museum to be figured. The work was continued thus for 

 more than a year, without my knowledge of the fact that Dr. B. G. 

 Wilder had previously been engaged on similar work while assistant of 

 Professor Agassiz. And it was not until about 1883 that the Director 

 of the Museum desired me to prepare for publication my own material, 

 and that accumtilated under Professor Agassiz's directions. It was 

 found that, in order to use the manuscript left by Dr. Wilder, many 

 changes would be necessary, and it was thought better on the whole not 

 to attempt to incorporate it with my own. Dr. Wilder's dissections have 

 been used as far as possible in the descriptions. They were figured by 

 Mr. Roetter, and included a representative of each of the following 

 genera : Scoliodon, Prionodon, Mustelus, Triads, Isurus, Odontaspis, 

 Alopias, Ginglymostoma, Scylliorhinus, Heterodontus, Acauthias, Rhina, 

 Pristiophorus, Pristis, Raia {R. Icevis), Dasybatus (Z). tuherculatus) , 

 Pteroplatea (^P . valencieiuiii) , Myliobatis (31. fremiyivillei and M. aquila), 

 Aetobatus, and Rhinoptera {JR. hrnsiliensis and R. jussieui). In addition 

 to these there were preparations of several types of which no use has 

 been made, as they had been duplicated in my own work. Chimsera 

 and Callorhynchus required no dissection ; a drawing of the latter had 

 been made by Mr. Roetter. The figures by this artist were made to 

 be lithographed, and were not at all suited to the engraver's process, 

 by which this publication was to be illustrated. Consequently outlines 

 have been used instead of his drawings. 



This leaves me responsible for all the text, and for the dissections 

 and sketches of Dicerobatus, Pteroplatea (P. liirundo and P. marmorata), 

 Dasybatus (Z). nudxis and D. dipterurus), Teeniura, Urolophus, Disceus, 



VOL. XVII. — NO. 2. 



