Pl. I. 



Figs. 1 — 5. Developnienlal stages of Raja radiata. 



Fig. 1 . Embryo from an egg capsule, tåken in Gulosen, Trond 

 hjemsfjord, February 1909. Total length 18 mm. On 

 the hook-shaped prolongation of the head there is a 

 small furrow forming the first indication of the olfac 

 tory organ. Under the hook the mouth is present as 

 an equilateral triangel. The eye may be seen as a 

 rounded proluberance at the base of the hooked pro 

 longation. Behind the eye there are 6 lissures, of which 

 the first one indicates the origin of the spiraeulum. 

 For fnrther description see p. 27. 



2. The anterior part in dorsal view of an embryo from 

 Gulosen, 1 h 1910. Total length of the embryo 23 mm. 

 (see lig. 7 in the lexte). Here the commeneing gill- 

 threads may easily be seen. The pectoral fins have 

 grown forward to the 5. gill-slit. 



3. From the posterior part of the embryo from Gulosen, 

 l li 1910, showing granular spots, possibly integumental 

 glands, at the edge of the dorsal and ventral embryonal 

 fins. The flaps of the dorsal fins commence to rise 

 out of the embryonal dorsal fin. 



4. Anterior part in dorsal view of an embryo from Gul- 

 osen, February 1909. Total length of the embryo 40 

 mm. The spiraeulum is seen behind the eye as a 

 tubular aperture. The pectoral fins have grown for- 

 ward to the 3. gill-slit. In the ventral fins there is not 

 vet any incurvation. See description on p. 28. 



5. The foremost part of an embryo from Gulosen, February 

 1909. Total length 50 mm. Here the loose flaps of 

 the pectoral lins have grown forward past the 1. gill- 

 slit. This figure shows the triangular oral disc, which 

 later grows together at the lateral edges with the ad 

 vancing flaps of the pectoral fins. See description on p. 29. 



