densely haired. Medial surface of basis produced 

 into blunt process, covered with hairs; mar- 

 ginal surfaces of every segment in each ramus 

 also covered with hairs. Spines on outer sur- 

 faces of exopods of leg 2 (fig. 16), leg 3 (fig. 

 17), and leg 4 (fig. 18) weakly developed, seti- 

 form, and naked. Intercoxal plate absent in leg 

 1, leg 3, and leg 4; coxa and basis not com- 

 pletely separated in leg 3 and leg 4. Leg 5 (fig. 

 19) uniramous, very rudimentary, 10 by 9 /x; 

 located at junction of "tail" and trunk and 

 armed with three long setae. Leg 6 absent. 



hnmature adult female. — Body (figs. 21-23) 

 noncyclopid, shaped differently in different 

 stages of metamorphosis; proportions of vari- 

 ous body regions also different in different 

 stages (see table 2) . 



Table 2. — Measurements of immature adnlt females taken 

 from Chilomycterus schoepfi off Cape San Bias, Fla., in 

 the Gulf of Mexico. 



Structure of appendages similar to mature 

 ovigerous female. Details of these immature 

 adult females are given in following section in 

 discussion of metamorphosis. 



Female copepodid. — Body (fig. 20) cyclopoid, 

 0.70 by 0.37 mm. (excluding setae on caudal 

 rami) ; no segmentation on cephalothorax and 

 urosome, but with clear distinction between 

 each two adjoining regions of four body 

 regions. Cephalothorax semicircular anteriorly 

 and rather truncated posteriorly; posterior sur- 

 face roughly separated into dorsal and ventral 

 portions. Second pedigerous segment (— neck 

 of adult), 0.08 by 0.26 mm., attached to center 

 of posterior surface of cephalothorax, carrying 

 leg 2 ventrally at anterior margin. Third pedi- 

 gerous segment, 0.13 by 0.26 mm., slightly in- 

 vaginated on both sides and incompletely sepa- 



rated from fourth pedigerous segment on dor- 

 sal surface. Fourth pedigerous segment, 0.12 

 by 0.26 mm., with posterior margin protruding 

 over about one-third of urosome. Urosome 

 (= "tail" of adult) 0.17 by 0.23 mm., carrying 

 inside a pair of seminal receptacles (or cement 

 glands ?) . Egg sac attachment area similar to 

 that in adult. 



Caudal ramus attached to posteroventral 

 surface of urosome, its armature as in adult. 

 Two sclerites on dorsal surface of third and 

 fourth pedigerous segment. Micropits present 

 on body surface (omitted in fig. 20). 



All appendages similar to those in adult 

 ovigerous female and immature adult female. 



Remarks 



In the vial labeled Cat. No. 38619 in the 

 collection of USNM are two specimens (one 

 decapitated) designated by Wilson (1911) as 

 the type specimens of Tucca corpulentus. 

 The trunk of the headless specimen appears like 

 the one shown in fig. 24, namely, squarish and 

 distinctly 3-lobed on its posterodorsal surface. 

 The head of this specimen was supposedly dis- 

 sected by Wilson for study of the mouth parts 

 and other cephalic appendages, and probably 

 was the source of his figs. 122-125. The other 

 specimen (with head) is, doubtlessly, the source 

 of his fig. 121. I have examined the latter speci- 

 men with great care in lactic acid. Neverthe- 

 less, I was not able to find any appendages that 

 are significantly different from those described 

 above. In addition, the posterodorsal surface 

 of the trunk is also 3-lobed, not as smooth as 

 illustrated by Wilson in his fig. 121. The cir- 

 cular appearance of this specimen is possibly 

 due to the fact that the parasite was somewhat 

 pressed (by the fin, on which the parasite was 

 attached, pressing against the body surface) 

 before preservation, because its trunk appears 

 unusually thin. The absence of pits or impres- 

 sions on body surface, one of the characters 

 cited by Wilson for establishing the new 

 species, is conceivably also due to mechanical 

 deformation prior to preservation. 



Consequently, as far as these two type speci- 

 mens are concerned, T. corpulentus does not 

 differ from T. impressus and should be synony- 

 mized with it. There are some inconsistencies 



CYCLOPOID COPEPODS OF GENUS TUCCA 



293 



