DEVELOPMENT OF THE PORBEAGLE SHARK. 



163 



logical sequence, and to interpret them in the light of my recent 

 observations, 



II. Record of Material. 

 Table I. contains a record of the captures of all Larana embryos 

 known to me, and in addition of the smallest free-living speci- 

 mens. It is apparent at the outset that from the time when the 

 embryo has attained a length of 25 cm. down to the time wlien it 

 is approaching readiness for birth (75 cm.), we have a fairly 

 complete series of records. None of the embryos in this series, 

 however, differs in any important developmental character from 



Table I. 



the others ; the period which they represent, in other woi-ds, is 

 mainly characterized by growth in bulk. The only record of an 

 earlier phase is that of Swenander (7), who states that the 

 stalk of the original yolk-sac was present as a mere shred in 

 embryos 5'5-6'0 cm. long. 



From the fact that the smallest known embryos (A) were 

 obtained in January, and that they measured not more than 

 6 cm., it may be inferred that fertilization takes place towards 

 the end of the year. In December and January again we 

 find embryos measuring 29*0 and 29*5 cm. (C, D) ; these have 



11* 



