PLATE II. EXPLANATION. 41 



Explanation of Plate n. 



Fig. A. Niphargus stygius (male), magnified. 



1. Accessory flagellum of Antenna of upper pair. 2. Mandibula. 3. Maxilla 

 of 1st pair. 4. Maxilla of 2nd pair. 5. Maxillary foot. 6. Natatory foot of 10th 

 pair. 7. Saltatory foot of 32th pair. 8. Last segment (female), with Caudal ap- 

 pendage and Saltatory foot of last pair. 9. Inner style of foot of same pair, 

 more magnified. 



Fig. B. Niphargus aquilex, magnified. 



Fig. C. 10. Bathyporeia pilosa, head and Antennae. 11. Accegsory flagellum 

 of Antenna of upper pair. 12. Mandibula. 13. Maxillary foot. 14. Foot of 

 1st pair. 15. Terminal joint of same, more magnified. 16. Foot of 2nd 

 pair. 17. Foot of 3rd pair. 18. Foot of 5th pair. 19. Abdominal foot of 4th 

 pair. 20. Abdominal foot of 5th pair. 21. Abdominal foot of 6th pair. 



Class Crustacea. Ord. Amphipoda. Fam. GammaridjE. 



Genus Niphargus, Schicedte, Act. Soc. Reg. Dan. a.d. 1851.^?. 26. 



Oculi nulli. Antennae superiores inferioribus longiores, flagello appendi- 

 cular! minuto, biarticulato. Pedes ultimi paris stylo interiori brevissimo, 

 exteriori valde elongato, biarticulato. 



1. stygius, Sch. I.I., et Comm. Soc. Reg. Dan. a.d. 1855, p. 350. 

 Dorso simplici : epimeris anterioribus segmenta sua altitudine subsequan- 



tibus : segmento nono omnium altissimo. — Long. 5 — 7 lin. (PI. II., 

 Fig. A. 1—9.) 



Inhabits the Grottos of Adelsberg and Lueg in Carniola ; in little pools 

 in the hollows formed by the dripping. It springs very nimbly, and is 

 difficult to catch, making for the bottom immediately when disturbed. 



2. aquilex, Sch. Comm. Soc. Reg. Dan. Id. 



Dorso carinato : epimeris omnibus segmento cujusque proprio altitudine 

 inferioribus : segmentis octavo nono decimoque altitudine subaequalibus. — 

 Long. 3—4 lin. (PI. II., Fig. B.) 



Obtained in considerable numbers, by pumping,~out of a deep well near 

 Maidenhead, in England, in the year 1853. 



Except for the differences mentioned in the diagnosis, and the inferior 

 size and more slender shape of the second species, the two are so like that 

 we may transcribe the description of the Grotto Niphargus to illustrate the 

 " Well shrimp" found in England. 



Niphargus Stygius. Elongated ; the length five times the greatest depth 

 from the back of the third segment to the lower edge of the epimeron ; some- 

 what compressed, the greatest breadth not equalling the height of the third seg- 

 ment; smooth, entirely without ridges or teeth; colour, snow-white. Head 

 scarcely one- twelfth of the entire length. The first five segments of nearly equal 

 length, each a little longer than the head; the following five gradually larger, 

 ninth the deepest of all ; the last three gradually diminishing. Epimera finely 

 scalloped on the anterior angle and lower margin, with a single bristle at each 

 indentation ; the first four pairs of them rather deeper than the corresponding 

 segments, subquadrate, with the angles and margin rounded, the third the 

 deepest of all ; the last three pairs decreasing in size, the fifth scarcely as deep 

 as its segment, with its lower margin deeply bisinuated, the sixth, which also is 



e 



