13. BOLEOPHTHALMUS. 101 



** Immature, with the ventral fins separate. 



b. c. Siam. From M. Mouhot's Collection. 



Var. /3. P. scHLossEKi, P. septejieadiatus, p. novemkadiatus, with 

 seven to nine dorsal spines. 



* Adult, with the ventrals united. 



a, b. Singapore. Seven or eight dorsal spines. 



c. Purchased of Mr. Frank. Seven dorsal spines. 



d. Batavia. Eight dorsal spines. 



e. Skin. Sea of Pinang. From Dr. Cantor's Collection. 



** Immature, with the ventrals separate, and one of the 

 specimens with the second dorsal spine slightly produced. 



/-/. Two to three inches long. India. Purchased. 



Var. y. P. TKEDECiMR.iDiATUs, with thirteen to fifteen dorsal spines. 



* Adult: unknown. 



** Immature, with the ventrals separate, and the second 

 dorsal S2)ine much produced. 



a, b. Three to foirr inches long. Siam. From M. Mouhot's Col- 

 lection. — Apparently taken with specimens b and c of Var. a. 

 c. Foiu' inches long. India. Presented by General Hard^Wcke. 



The number of spines and the form of the anterior dorsal fin are 

 subject to great variation, as in Periophthalmus hoelreuten. The 

 greatest differences may be observed in quite young specimens pro- 

 cured at the same time and from the same locality, and otherwise 

 agreeing with one another in every respect. "Whether the produced 

 first dorsal spine, a character which nearly always coincides with a 

 great number of spines, is a peculiarity of one sex only, I do not 

 know, but it is very probable. Another peculiarity of this species 

 is, that the ventral fins are separated from each other during the 

 immature period of the fish, but are united in its adult state. 



AH these diff'erences, partly accidental, partly dependent on the 

 state of development, have been misconstrued, and have given rise 

 to five specific denominations. 



13. BOLEOPHTHALMUS*. 



Boleophthalmus, Cuv. ^- Vol. xii. p. 198. 



Body subcylindrical, covered with very small or rudimentary scales ; 

 head oblong, -w-ith the cleft of the mouth nearly horizontal, and 

 with the upper jaw somewhat longer. Eyes close together, very 



* 1. Boleophthalmus dentatus, Cuv. S[ Val. xii. p. 208. pi. 355. — Bombay. 



2. campylostomus, Bichm-ds. Ichfh. Chin. p. 209. — Canton. 



3. laokus, Cuv. ^- Val. xii. p. 214. — Ma'acca. 



