ee ee a m TAMEN 
UTE ns cor own usdea o beu Mc.» sbi Sos doe la cedo ligt ae iM i RC ak a ML en I al a 
1894.] Lepidosirenids and Bdellostomids. 583 
“Bdellostoma dombeyi 6 gills. 
" » 6-7 indicating the sides of the body 
« a 7.G [ Upon which the respective num- 
bers occurs. 
It will be noticed that there is a great gap from 7 to 10 
which has been straddled, but for which there is not the 
slightest observational basis. The logical fallacy involved is 
too obvious to need more than pointing out, 
On one hand out of 354 specimens examined by Dr. Ayers, 
208 had 12 pairs of gills and 104 had 11 pairs of gills, while 
26 had 11 or 12 on one side. Not a single one had less than 11. 
No specimen with a smaller number than 10 has been record- 
ed from the Pacific Coast. 
On the other hand, of many specimens obtained in New 
Zealand, South Africa, etc., all had 7 or 6 and none had more. 
Are not these facts sufficient to prove the distinctness of the 
two types? 
(1) There is a gap of from 7 (maximum) to 10 (minimum) 
at least, between the number of gills of the two types. (2) 
The range of variation, considerable as it is, is limited in both 
directions. (3) The differences in numbers are associated with 
differences in geographical range. Certainly, then, the two 
forms are specifically distinct. Are they not generically dis- 
tinct ? 
Dr. Ayers has truly remarked (p. 152) “It seems to have 
become a settled belief among the large majority of zoologists 
of both morphological and systematic proclivities, that the 
number of gills found among vertebrates never rises above 
