Diversity in the Scutes of Chelonia. 53 



backward pointing snout. In accord with the reduction of the parts 

 just above it, the upper jaw is much shortened and iiattened from 

 the front so that it extends across from side to side in a more direct 

 way than usuaL The lower jaw, however, has about its usual form; 

 so that, instead of being, as usual, enclosed mthin the upper jaw, it 

 protrudes well beyond the upper. A somewhat similar embryo has 

 already been alluded to (No. 36), Table VII, A). All three are 

 further characterized by the very slight development of pigment. 



The most remarkable defonnity noted is that of Xo. 100 (Figs. 

 93 and '.).")). The lower jaw forms a pointed horizontal projection 

 from the ventral part of the ht ad, and on the dorsal aspect of this 

 projection is a longitudinal slit representing the mouth. iVbout 

 halfway up the anterior aspect of the head is another pointed pro- 

 jection (snout {). There is no external evidence of eyes. The body 

 is characterized by a reduction of its dorsal part. The carapace 

 consists of two scutes with a smaller ovoid scute anterior to these (Fig. 

 95). On each side a bridge of one scute connects the carapace 

 with the plastron, which possesses the full number of scutes. Pos- 

 teriorly the plastron (Fig. 93) bends sharply dorsally in conse- 

 quence of the reduction of the dorsal region. The dotted line in 

 the figTire indicates the region of the angle. Between the upper pos- 

 terior end of the plastron and the posterior end of the carapace is the 

 tail bearing the anus on its dorsal aspect. The heart, lungs, stomach 

 and intestine lie external to the umbilical opening. The limbs are 

 situated dorsally. 



Among the smaller embryos wath scutes undeveloped and, there- 

 fore, not included in the table was a fifth deformed embryo from the 

 same nest. It needs only an allusion here. The body is reduced, 

 and rounded, and the limbs appear rudimentary. 



In view of the excessive proportion and degree of abnormality 

 observed in this lot of embryos, the conditions of development should 

 be described. The original lot of eggs was brought to the labora- 

 tory by a fisherman. According to his statement they were a mixed 

 lot from two nests taken the preceding day. Some of them had dried 

 somewhat and the lot was regarded as unpromising. However, they 

 were placed in a single nest on the island made as usual in imita- 



