214 HAROLD HEATH. 



33 cm. (13 inches) when alive and in a resting condition and 

 weighed seven grams less than two kilograms (4.4 Ibs.). 



Regarding the breeding habits little may be said at the present 

 time. On three different occasions I have found males shedding 

 their sex products in the latter part of February and at this time 

 the females are distended with eggs. The oviduct is provided 

 with an albumen gland in all essential respects like that of Ischno- 

 chiton magdalenensis (Heath, '99) and it is reasonable to suppose 

 that like this last-named species Cryptochiton lays its eggs im- 

 bedded in a gelatinous envelope. In the early part of the summer 

 the young have attained a length of from 10 to 22 mm., and as 

 has been described in a previous paper (Heath, '97) the shells 

 are still exposed. The mantle of these small individuals .is 

 usually of a yellow or orange color, exceptionally light green, 

 and is beset with more or less definitely arranged yet scattered 

 groups of crimson spicules characteristic of the adult. As these 

 increase in number the general shade ordinarily changes to a 

 brick red * not infrequently blotched with patches of white or 

 purplish-white that usually disappear by the time the animal has 

 become sexually mature. 



Middendorff was the first to discover the kidney in the chitons 

 yet it was with some hesitancy that he applied this name to it, 

 as his observations were very incomplete. However, it must be 

 said they are more perfect than some of his critics have supposed. 

 He correctly states that the excretory canals unite in front of the 

 pericardium in " einem geschlossenen Bogen " (p. 73) and he 

 accurately locates the glandular portion, but the fact was never 

 discovered that this latter division is penetrated by two canals, 

 one of which connects with the pericardium while the other 

 opens to the exterior. 



The kidney holds the usual position at the sides of the visceral 

 cavity and posseses the form of a very slender U, the free 

 extremities terminating in the reno-pericardial, and external 

 openings, while the opposite rounded end is situated at the level 

 of the anterior margin of the third valve of the shell (Fig. i). 



1 Middendorff described his specimens as yellowish brown but this was due to the 

 fact that the tufts of bristles had been worn away exposing the mantle to an abnormal 

 degree. 



