38 A. E. HEFFORD. 



chromatophore. Ehrenbaum states that the anterior group is usually 

 confined to the ventral half of the body, but I have very often found 

 it possessing a well-marked dorsal bar. The extent and intensity of 

 these bars and groups of pigment, however, are subject to some 

 variation. With the absorption of the yolk the post-anal pigment 

 diminishes, especially in regard to the dorsal chromatophores, and 

 when the yolk is entirely absorbed the latter have generally — though 

 not always — entirely disappeared, leaving three relatively small chro- 

 matophores along the ventral contour corresponding to the three 

 previous groups. At this stage the pectoral fins are well developed ; 

 but the ventrals, which soon afterwards become such a conspicuous 

 feature of the post-larva, are rudimentary. My 0. mustela eggs were 

 taken for the most part in Plymouth Sound and some in Cawsand 

 Bay, while none were taken in more open water than AVhitsand Bay, 

 which is in keeping with the littoral haunts and the penchant for the 

 vicinity of brackish water of the parent fish (cf. Holt, lid, p. 143). 



Onos, SjKcies A (? tricirratus, Bl). 



Two eggs which may probably be referred to this species occur in 

 my samples, one taken on 28th June 3 miles S. by W. of Eame Head, 

 and the other taken on 30th August 3 miles W.N.W. of Eame Head. 

 The identification is chiefly based upon the similarity of the larva to that 

 of 0. tricirratus, described by Pvaffaele (20, pp. 37 and 38, Tav. I, Figs. 26 

 and 27; Tav. Ill, Figs. 2 and 3) from an egg of 0*74 mm. diameter, which 

 had an oil-globule of 0*2 18. The larva is characterized by the possession 

 of less pigment than 0. mustela or 0. cimhrius. It is practically limited 

 to one clearly defined zone of black pigment across the middle of the 

 post-anal part of the body and a line of peritoneal pigment dorsal to 

 the gut {op. cit., Tav. Ill, Figs. 2 and 3). The earlier of my eggs had 

 a diameter of 0-84 mm., and the later one 0'78 mm. The oil-globules 

 measured respectively 0'16 and 0145 mm. The embryonic pigment 

 spots, which are small at their first appearance, become in the later 

 stages relatively large in size, although few in number. The isolated 

 mid-post-anal group of chromatophores is very conspicuous. In my 

 second specimen I noted that this group consisted of six ventral chro- 

 matophores with three dorsal and two lateral ones, which, before 

 hatching took place, formed a dense band around the embryo by their 

 enlargement and partial fusion. Black appears in the eyes shortly 

 before hatching. In both specimens only one chromatophore was to 

 be seen over the oil-globule. The newly hatched larva from my 

 later egg (Fig. 14) measures 2'32 mm., of which 0'94 mm. is pre- 

 anal. That from my June egg, measured when about one day old, 



