LARVAL FORMS OF FRESH-WATER MULLET 



417 



Cow Creek i^ "I'le east of Sainsulix Junction on 

 Florida Hijjhway 75, Volusia Vo., captured Feb. 

 21, 1948; 1 specimen (32.4 mm.) from Volusia 

 Co.. taken in 1948; 1 si)ecimen (81.5 mm.) 

 from Cedar-(^ow Creek, Volusia Co., taken in 

 June 1949; 3 specimens ((Ki.l, ()8.0, and 75.5 mm.) 

 from Cow Creek, Volusia Co., taken on May 23, 

 1949; 4 specimens (94.4, 96.5, 105.0, and 105.3 

 mm.) from an artificial fresh-water pond near 

 St. Aujrustine Beach, St. Johns Co.. taken August 

 30, 1949; 2 specimens (62.0 and 63.8 mm.) from 

 Spruce Creek, Volusia Co., taken April 29, 1950; 

 and 1 specimen (26.7 mm.) from Spruce Creek, 

 Volusia Co., taken Nov. 8, 1951. 



METHODS 



Metliods employed aboard the vessel Theodore 

 \. GUI are given by Anderson, Gehringer, and 

 Cohen (1956). 



Descriptions are based on preserved material, 

 and measurements of larvae up to about 35 mm. 

 standard lengtli were made with a stereoscopic 

 microscope and a micrometer eyepiece. The 

 larger specimens were measured with calipers. 

 Original measurements were used in constructing 

 tlie graphs to portray rates of growth of various 

 body parts, and changes in body proportions. 



DESCRIPTION 



In general appearance tliese sea-stage young of 

 A. nwnticola closely resemble the sea-stage young 

 of both M. curema and M. cephalus, the most strik- 

 ing difference being tliat ^4. monticola appears 

 much more slender and with a longer caudal 

 peduncle. All are heavily pigmented and appear 

 blackisii. Figure 2 illustrates a 31.3-mm. speci- 

 men. Observed under magnification, the presence 

 of ctenoid scales quickly separates A. monticola 

 from these two species of Mwgil. 



FINS 



Dorsal: — All e.xcept two of the 34 specimens 

 examined Iiad a dorsal Hn formuhi of IV-I, 8. 

 One of the Florida specimens (96.5 mm.) had 5 

 spines in the first dorsal, arranged in a peculiar 

 manner so as to appear as two fins; the 1st, 2d, 

 and 3d spines were connected by membranes, the 

 3d and 4tli spines were not connected by a mem- 

 brane, but the 4th and 5th spines and the 5th 

 spine and the body were connected by membranes 

 (tliis aj)i)ears to have resulted from an abnormal 

 division of the 3d spine, altliough all spines were 

 of normal size). One specimen from Cuba (64.5 

 mm.) had only 6 soft rays instead of the usual 8. 



Anal: — All except one of the specimens ex- 

 amined had an anal fin formula of II, 10 (one 

 Florida specimen, 81.5 mm. had II, 9). In figure 

 3 the details of the anal fin of cleared and stained 

 specimens of A. mo-ntieola, M. ewema^ and M. 

 cephalus at comparable sizes (about 30 mm.) are 

 illustrated. Both spines and the first soft ray in 

 A. monticola are shorter and more slender than 

 in .1/. curema and M. cephalus. A notable dif- 

 ference at this size occurs in the last ray. In both 

 M. curema and M. cephalu.s tliis ray has two main 

 branches, each of which is in turn deeply forked, 

 while in A. monticola only the anterior main 

 branch is forked. 



A difference in the number of anal spines re- 

 ported for ^4. montkola occurs in the literature. 

 Jordan and Evermann (1896) on page 809 in 

 their key to the genera of Mugilidae indicate 2 

 anal spines for Agonostomus Bennett; on page 

 818 under tlie generic description is the statement, 

 "Anal spines usually 2, the first soft ray slender 

 and often taken for a spine"; pages 819 and 820 

 describe 4 species of Agonosfomus, including A. 

 monticola, each of which is given an anal fin 

 formula of III, 9. Evermann and Marsh (1902) 



Figure 2. — A young Agonn.itomuit nioiitii-oln. 31.3 mm. long, capturetl in the open ocean. 



