BDELLOSTOMA DOMBEYI, LAC. 143 



The number of teeth in Bdellostoma varies as much, if not 

 more, than the number of gills, so that the only two "constant" 

 characters which Miiller could find upon which to base a classi- 

 fication are both of them extremely variable. The limits 

 of the variability of the teeth, so far as known, are as 

 follows : 



Bdellostoma from the Cape of Good Hope, 6-7 gills, |||, 



1 1 ! 1 1 1 2 I 1 2 



IT Iri' IT ITU- 



Bdellostoma from coast of Chili, 10 gills, ! f | a y (Lacepede), 



\\ \\> 11 it- 



Bdellostoma from coast of California, 11-13 gills, -||f, \\ \\. 



The California series which I have counted is the only one 

 extensive enough to give opportunity for the observation of 

 the variations, although M tiller evidently had nearly extreme 

 forms in the three individuals whose dental formulae he re- 

 corded. 



In 22 individuals with n gills I found the dental formulae to 

 be as follows:-! Y- i 1 HI&- 4 V" > * W> * H|H. 



1 uiv-- i !-. ! H H. 3 HIH. ! \\ H. 5 HIH. 



!tt|H. IV- IV' 2 1? \\' 



In 6 1 individuals with 12 gills the following dental formulae 



occurred:-! f |^, ! ||, 8 ||V-, 1 T %|V>, 1 T ^|ii 2 |l- 



i l*|t. ! HI A. 10 - 4 U1V-. 6 HIM. 7 V- H. 

 i -|V-. i HIH. ! |V> i H V-' 10 HIH. 3 HIH. 



1 ll|l|, 1 if | |f. These counts were made on consecutive 

 animals as they came from the trawl line, and must represent 

 fairly the dental conditions of Bdellostoma in the Bay of 

 Monterey. Two things are apparent. First, there is not the 

 least relation between the number of gills and the number of 

 teeth ; and, second, the teeth are subject to much greater 

 variation than the gills, notwithstanding they belong to the 

 so-called hard parts. Size and age do not affect the dental 

 formula. 



On combining the dental formulae of the u-gilled and 12- 

 gilled variations, we find the following numbers to obtain for 

 the 86 individuals whose dental formulae I have carefully 

 counted on both sides of the dentiferous plate. 



