. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. pplvic splinl L . 5 mm J Figure 3. Modified scale in caudal gland of $ lotabrycon proecox (drawn from an alizarin preparation). Arrow points to separately ossified process which may represent a second modified scale. depth (range , average ) tends to be greater tlian in fenial(\s and immature specimens (range , average ). In tlic- first eiglit or ninc> segmented anal fin rays bear liooks and form a distinet lobe; pelvie fins relative!) longer and bearing hooks; peKie fin leng
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. pplvic splinl L . 5 mm J Figure 3. Modified scale in caudal gland of $ lotabrycon proecox (drawn from an alizarin preparation). Arrow points to separately ossified process which may represent a second modified scale. depth (range , average ) tends to be greater tlian in fenial(\s and immature specimens (range , average ). In tlic- first eiglit or ninc> segmented anal fin rays bear liooks and form a distinet lobe; pelvie fins relative!) longer and bearing hooks; peKie fin length , (average ). In females anal and pebie fins bookless; peb'ic l(>ngth , average No other e\ident differenees in pro- portional measurements between sexes. Of 12 male specimens in the type series, the six largest individuals range from mm standard length, whereas out of only 8 females and immatinx^s, the largest female, at mm, is considerably larger. Modified caudal structures in males (Figs. 1-3). Twelve of the 20 specimens in the t)pe series are identified as males because tliey bear well-developed hooks on the anal and pebic fins and have a "caudal ; In lotabrycon the caudal modifications consist of a highly modified scale supporting a large caudal pouch and a muscle with extensive attachments to the proximal half of the upper caudal lobe. The modified scales on opposite sides of the caudal fin are mirror images. It is questionable whether the posteriorly di- rected process indicated by an arrow in. isctiiac process Figure 4. Left pelvic fin and girdle of .i lota- brycon praecox, showing distribution of hooks on fin rays (ventral view). Figure 3 represents a separate scale. They are well developed and of similar morphol- ogy in all the males in the t)'pe series. The principal caudal rays are unmodified, except in size, the caudal fin being some- what larger in males than in females. The upper procmrent caudal
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