. Bulletin. Natural history; Natuurlijke historie. 76 PEABODY MUSEUM BULLETIN 43. Fig. 30. S. greenwoodi. A, dorsal ridge scales of S. greenwoodi, holotype YPM 8970; B, frontals and parietals of YPM 8970. Scale = 1 cm. than they are in S. tenuiceps (Fig. 30). The first 3 scales lack spines completely, and the 4th and 5th scales have very broad, short spines. The 6th through 12th scales have large spines and bulbous bases, with only the spines covered by ganoine. Posterior to the 12th dorsal ridge scale, the scale bases become more rounded and flattened with very prominent long spines, very muc
. Bulletin. Natural history; Natuurlijke historie. 76 PEABODY MUSEUM BULLETIN 43. Fig. 30. S. greenwoodi. A, dorsal ridge scales of S. greenwoodi, holotype YPM 8970; B, frontals and parietals of YPM 8970. Scale = 1 cm. than they are in S. tenuiceps (Fig. 30). The first 3 scales lack spines completely, and the 4th and 5th scales have very broad, short spines. The 6th through 12th scales have large spines and bulbous bases, with only the spines covered by ganoine. Posterior to the 12th dorsal ridge scale, the scale bases become more rounded and flattened with very prominent long spines, very much like the posterior scales of the S. micropterus group (Olsen and others 1982). The last scale in the series is a large oval plate that abuts the first unpaired fulcrum on the leading edge of the dorsal fin. The total number of scales in the dorsal series, including the predorsal scale, is about 22. This species is the most slender and streamlined of the S. tenuiceps group. The head is small relative to others in the S'. tenuiceps group, and the slope of its forehead with respect to horizontal is about 30-40°. Overall body form is most clearly seen by comparison of outline drawings (Fig. 27) of each of the six species in this genus. By visual inspection or by superimposing a tracing of S. greenwoodi on outlines of the other species (all at the same standard length), one can easily see that S. greenwoodi is more slender than any other species (Fig. 29). These morphometric data are summarized in Table 27. There are 33 or 34 (usually 34) lateral line scales. The pelvic fin originates at the 8th or 9th (usually 9th) scale row, the dorsal fin at row 20 or 21, and the anal fin at row 18 or 19. The scales along the dorsal and ventral midline of the caudal peduncle are enlarged. Rarely, there are intercalated scale rows dorsal to the lateral line and anterior to the dorsal fin. The scales are largest in the anterior flank region and around the lateral line. They decrease in size both
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