66 EXPLANATION OF PLATES. 



with numerous long, stout setae, some of which are branched. 

 First four pairs of swimming feet with three-jointed branches 

 and a voluminous base ; fifth pair rudimentary. Male. — 

 Anterior antennae five-jointed, with a geniculation between the 

 fourth and fifth joints, apex of the genital segment elongated. 



Genus Monstrilla, Dana. 



Closely allied to Thaiimaletis : mouth placed far back ; 

 between the genital segment and the furca there are three 

 segments in the male, but in the female the first of the three 

 is incompletely separated or quite coalescent ; the fifth pair of 

 feet in the inale is in the form of a tolerably long bristle (or a 

 stump) ; the apex of the genital segment in the male short in 

 comparison with its ordinary-sized base; furca in both sexes 

 with five or six setae. 



EXPLANATION OF PLATES. 

 Plate i. 



AmEIRA AIMPHIBIA. $ 



Fig. I. Female seen from left side X 140. 



2. Antennvile i 



' X 300. 



3. Inner branch of antenna ) 



4. Mandible \ 



5. Maxilla )- X 440- 



6. Anterior footjaw ) 



7. Posterior footjaw \ 



8. Foot of first pair / 



. . , ■ } X 300- 



9. ,, third pair 



10. ,, fifth pair 



11. Last abdominal segment and furca X 240. 



Cyclops eboracensis. ? 



12. Antennule ) 



13. Foot of first pair >- X 240. 



14. Caudal lamina ) 



Pseudothalestris MONENSIS. 



15. Foot of third pair ^ 



16. Antennule j 



