I 



MUSEUM OF COMPAMATIVF': ZOOLOGY. 83 



each ; and still lower down are from five to seven additional transverse 

 series, extending well down on the ventnd surface of the body. It is 

 possible that these lateral series are derived from a segmentally arranged 

 type ; but if to they have certainly deviated greatly from the typical 

 arrangement, as they also vary both in the number of series and in the 

 number of papilhe in each series. The papilkv here are considerably 

 smaller, on the whole, than those of the head. There are, finally, a 

 number of papillae scattered around the bases of the fins, both pectoral 

 . and pelvic. 



In Clevelandia there are about twenty-five transverse series on the 

 sides of the body very uniformly segmentally arranged, being situated 

 on the inter-myotomic septa. The series contain an average of about 

 five papillae each, though the number varies considerably. I have 

 worked out the precise arrangement of the series on the septa, — for 

 not quite all the septa have papillae, — and of the number of papillae 

 to each series in a considerable number of specimens, as it has appeared 

 to me that this may have considerable morphological significance. It is 

 not necessary for my present purpose, however, to give the results in 

 detail. It is worthy of mention that the transverse series on the body 

 of Clevelandia are situated in shallow ditches, the anterior wall of these 

 being deeper and more abrupt than the posterior. In no case have I 

 been able to find the papillae situated in canals, or in grooves that 

 approach canals, as is so common in fishes, and is said to be the case in 

 Gobius niger, by Merkel ('80, p. 28). All writers agree, however, that in 

 the genus Gobius by far the greater portion of the papillae are free on the 

 surf^ice of the body (F. E. Schultze, '76; Merkel, '80; Solger, '80). We 

 know from the last two of these authors that both the genera Gobius and 

 Gobiodon have free transverse series of papillae on the sides of the body. 

 "With reference to this subject, Solger ('80, p. 378) says : " Bei Gobius 

 konnte ich 'Querreihen von 3-7 Organen' constatiren ; auf Beziehung 

 der Organreihen zur Metamerie des Leibes achtete ich .damals leider noch 

 nicht. Auch Gobiodon hat am Rumpfe freie Seitenorgane, die in Quer- 

 reihen auf Coriumpapillen stehen und hochst wahrscheinlich durchweg 

 segmental angeordnet sind." And Merkel ('80) shows three of these 

 series in his Figure 4, Taf. IV. 



It being, then, evident that so many of the near relatives of Typhlo- 

 gobius are provided with sense papillas on the sides of the body, the 

 question at once arises whether any are found in the corresponding 

 region on the blind fish. Very naturally it was to the smallest speci- 

 mens in my possession that I turned to begin the search for them. On 



