SOME TRISir GASTBBOSTET. 



113 



1 specimen 2*1 inclies 1 



long I D- 4/10, P. 10, V. 0, A. 1/9, C. 12. 



1 specimen 1*6 inch ] 



long }^- 2/9. P- 10= V. 0, A. 1/9, C. 12. 



In the specimen with only two dorsal spines the seventh and 

 ninth were visible, the remainder not appearing above the inte- 

 gument. 



In examining the specimens wherein ventral spines existed, 

 they, as a rule, were not one half the length, of the pubic plate ; in 

 one specimen tlie spine on one side of the body was one third 

 shorter than its fellow on the opposite. In those wherein no 

 ventral spines existed, the pubic plate was also absent, and, as a 

 natural result, the spines which arise from it were likewise 

 deficient. 



further extended investigations are necessary to solve the ques- 

 tion, whether these fishes which are resident far inland are subject 

 to an arrest of development in their ventral spines and pubic 

 bones, or Avhether those which live nearest the coast have, as a 

 consequence, an increased development of offensive or defensive 

 armature. 



Diagrams of Stickleback and ventral plates. 

 A 



Fig. A, abnormal example of Gasterosfeus pungitius ; B, ventral spines &c. of 

 specimen of G. aculeatus ; C, ventral spines &c. of second specimen of G. aculeatus. 



G. ACULEATUS, LiwKBus, Yarrcll, Gunther, Couch, 8fC, 



D. 3-4/11-12, P. 10, V. 1/1, A. 1/8-9, C. 12. 



Without entering into any detailed description of the fish of 

 this species or its synonymy, I will merely advert to such varieties 

 as were captured. Out of upwards of two hundred specimens, none 



