HYNOBIIDAE. 451 



slits and reduce the original one, so that the end result is a transverse 

 slit. The process of change has not been observed, but as a completely 

 graded series can be found to connect the most extreme types, it seems 

 logical to suppose that there is an actual change in the shape of the 

 vent in individuals. All young have the vent of the female type. 

 The simplest type of male vent is a longitudinal slit with a small 

 papilla at the anterior end. This papilla gives the vent a Y-shaped 

 appearance, the two arms of the Y being very short; next in order of 

 complexity is the above condition with the addition of two lateral slits, 

 directed obliquely forward, nearly as long as the median slit, and 

 meeting it or the arms of the Y near the point of forking. A third 

 type lacks the median slit, but otherwise is like the form just described 

 and is somewhat M-shaped, or X-shaped, the exact form depending 

 on the length and obliquity of the two lateral slits, which may be 

 almost parallel or may make an angle of almost 180 degrees. These 

 various conditions are subject to many minor changes. They are not 

 specific, as I have observed the same series of conditions in several 

 different species of Hynobius. 



In Onychodactylus two pairs of slits directed obliquely forward meet 

 the longitudinal slit in both sexes. 



In Batrachupcrus there is an irregular star-shaped or cruciform 

 arrangement of the slits. 



Color pattern when present is in the form of a light dorsal band, 

 but this is often visible only on the middorsal line of the tail. This 

 light band is most prominent in Onychodactylus and in H. kcyscrlingii. 

 In most of the species there is no definite color pattern, and the animals 

 are marbled or spotted with dark and light in varying proportions. 



The habits of Batrachupcrus and of Pachypalaminus are unknown. 

 Of Onychodactylus we know only that it breeds in the spring and that 

 it frequents mountain brooks. Ranodon lives in mountain brooks, 

 breeds in the spring, and lays eggs in spindle-shaped sacs attached to 

 the under side of stones in streams. Hynobius lives on land, goes to 

 ponds in the spring to breed, and lays eggs in spindle-shaped sacs 

 attached to objects in the water. The eggs are pigmented, of small 

 vitelline content, and the larvae emerge in a very immature condition. 

 Save for the external fertilization, Hynobius, in its habitat reactions 

 and breeding habits, resembles the common American Ambystoma 

 maculatum. 



Measurements are in millimeters. The head is taken from the tip 

 of the snout to the gular fold; the body from thence to the posterior 

 angle of the vent; and the tail from that point to the tip. When I have 



