i8i 



5. Calanopia americana Dahl. Plate XLVIII, figs. 11 — 15. 



Calanopia americana Dahl, [894, p. 21, pi. 1, figs. 23 — 26. 

 Calanopia americana Giesbrccht & Schmeil, 189S, p. 132. 



The two sexes of this species are easily separated from the other smal! forms of Calanopia 

 by the structure of the fifth pairs of feet. 



The combined length of the abdomen and furca of the female is slightly less than one- 

 half of the total length of the ccplialothorax, from the frontal margin to the base of the crenital 

 segment. The second joint of the abdomen is nearly as long as the genital segment. It is 

 twice as long as broad. The furcal joints are two and a half times longer than broad. The 

 spiniform projections of the last thoracic segment are comparatively short. 



The fifth pair of the female is symmetrical. The exopodite is one-jointed. The ape\ of 

 the joint terminates in three moderately strong spines. The middle spine is considerably longer 

 than either of the other two spines. This spine is proportionally much shorter than the long 

 spine on the apex of the exopodite of the female fifth pair of Calanopia minor, or Calanopia 

 aurivillii. It does not appear to be plumose (Plate XLVIII, "fig. 13). 



Length of female, 1,3 mm. 



The inner margin of the second joint of the basiopodite of the left side of the male 

 fifth pair is inflated at the proximal end. The swollen part is produced into a prominent tooth- 

 like process. The second joint of the left exopodite is comparatively long. It is equal to two- 

 thirds of the length of the first joint. The claw-like second joint of the right exopodite is 

 furnished with a distinct tooth. The first joint is very different in shape from that of the male 

 of Calanopia minor, or Calanopia aurivillii. There is also a deep incision at the base of the 

 thumb-like process that is not present in the other two species (Plate XLVIII, fig. 15). 



Length of male, 1,23 mm. 



The apical portion of the second pair of maxillipedes of both sexes is composed of four joints. 



Dahl's type specimens were fonnd in plankton collected at the mouth of the Tocantins 

 River, a branch of the Amazon Estnary. The illustrations given in this report are from specimens 

 obtained from plankton collected in 1903 at Hamilton, in the Bermuda Islands, by a brother 

 of Professor Herdmax. 



6. Calanopia aurivillii Cleve. Plate XLVIII, figs. 16 — 20. 



Calanopia aurivillii Cleve, 1901, p. 37, pis. II & III. 

 Calanopia aurivillii Thompson & Scott, 1903, p. 251. 



This species bears a close resemblance to Calanopia minor and to Calanopia americana , 

 but it is quite distinct from either of these forms. 



The spiniform projections of the last thoracic segment are moderately long. The combined 

 length of the abdomen and furca of the female is distinctly longer than one-half of the total 

 length of the cephalothorax, from the frontal margin to the base of the genital segment. The 

 second segment is slightly longer than the genital segment. It is nearly three times longer than 

 broad. The furcal joints are almost twice as long as broad. 



