426 



BULLETIN OF THE BUREAU OF FISHERIES. 



Larval development. — The incubation period at laboratory temperature occupies 

 approximately five days. The newly hatched larvae (fig. 51) are approximately 2 mm. 

 in length and almost transparent. The remaining yolk mass is opaque. The air 

 bladder is already apparent at the posteriodorsal aspect of the yolk mass. The dorsal 

 fin fold has its origin relatively far posteriorly. Both dorsal and ventral fin folds are 

 continuous. The depth of each fold does not exceed half the depth of the body at the 

 level of the vent. The vent is located less than half the length of the body from the 

 posterior end. A few small pigment spots occur just above the vent and at the base of 

 the veritral fin fold posterior to the vent. 



Figure 52 illustrates a larval fish 3 mm. in length. The yolk is completely absorbed. 

 The body remains almost transparent. The line of pigment spots at the base of the 

 ventral fin fold is somewhat more conspicuous than in the newly hatched larvse. 



Young fish 10 mm. in length (fig. 53) show many of the diagnostic characters 

 of the species but remain almost free from pigment. The air bladder is still apparent 

 microscopically. The head is gradually assuming the shape characteristic of the species. 

 The fins are well differentiated and the sucking disc formed by the ventrals is well 

 developed. 



CTENOGOBIUS STIGMATICUS. SCALLOPRSH. 



Spawning. — Like the related species, Gohiosoma bosci, this species was spawning in 

 Mullet Pond throughout August. As in the case of the former species, also the majority 



CIENOCOBroS STIGMATICUS. 



Fio. 54. — ^Mature un- 

 fertilized egg. X 

 60. 



Fig. 55. — Egg with fully devel- 

 oped blastodisc (bd); y, yolk. 



Fig. 56. — Ej^g with 

 blastoderm of 2 

 cells. 



Fig. s7.— Egg with 

 blastoderm of 4 

 cells. 



of the females taken were already spent. Obviously, the height of the spawning 

 season occurs earlier in the summer. 



Eggs. — The mature unfertilized ova (fig. 54) are very small, having an average 

 diameter of approximately 0.3 mm., and somewhat irregular in form. They are yellow 

 in color and highly translucent. Each ovum is attached in the ovary by a slender 

 peduncle composed of very minute threads inserted in the egg membrane. When 

 the female is stripped T:he eggs do not remain aggregated. They are only slightly 

 adhesive. Their specific gravity is very little greater than that of sea water. The 

 egg membrane is thin and delicate and is usually drawn out into a blunt apex at the 

 insertion of the peduncle. Except on this side the egg membrane appears closely 

 applied to the vitelline membrane. These eggs are characterized by a relatively enor- 

 mous amount of protoplasm and very little yolk. The transparent yolk mass usually 

 rests in the center of the mass of protoplasm, but in some eggs it occupies a some- 

 what eccentric position. 



