EMBRYOLOGY AXD LARVAL DEVELOPMENT OF TELEOSTEAN FISHES. 423 



Figure 42 illustrates a young fish 1 1 ram. in length. At this stage the j'oung exhibit 

 some of the characters of the adult. The characteristic number of rays are present 

 in the soft dorsal and anal fins. The spinous dorsal is not yet fully differentiated. The 





5> 



Fig. 40. — Xewly hatched fish, actual length 5 mm. 



Fig. 41. — ^Young fish 9 mm. in length. 



Fig. 42. — Young fish 11 mm. in length. 



KIRTLANDIA VAGRANS. 



color remains lighter than that of the adult. The sides are becoming distinctly silvery, 

 but the pale green on the back, characteristic of the species, is not yet apparent. 



GOBIOSOMA BOSCI. NAKED GOBY. 



Spawning. — This relatively obscure species was found spawning in Mullet Pond 

 throughout August. The majority of the females taken during this period were already 

 spent. Only occasionally was one found ripe for stripping. Obviously the height of 

 the spawning season was past. 



Eggs. — The mature unfertilized ova (fig. 43) are approximately spherical in form and 

 about 0.5 mm. in diameter. They are yellow in color and opaque.' Their specific 

 gravity is greater than that of sea water. In the ovary they are attached to a central 

 rachis by a thick peduncle composed of bundles of minute hairlike threads and inserted 

 in the egg membrane. When stripped from the female they remain aggregated in a com- 

 pact clump. The egg membrane is comparatively thin and closely applied to the vitel- 

 line membrane. 



As soon as fertilization has taken place the egg membrane begins to expand and 

 gradually assumes an elliptical form. When fully expanded the major axis is 1.2 to 1.4 

 mm. in length, the minor axis 0.5 to 0.7 mm. The point at which the peduncle is inserted 

 remains at one pole of the major axis. The egg remains located near one pole of the major 

 axis where it lies in a cavity the volume of which is somewhat greater than its own. 

 The wall of this cavity is indicated by a dotted line in figure 44. It is indicated also at a 

 later stage in figure 48. 



Embryology. — The volume of protoplasm is considerably greater in proportion to the 

 volume of yolk in these eggs than in the more typical teleostean eggs described above. 

 In the unfertilized egg the protoplasm is disposed in a layer of uniform thickness investing 



