98 Dr. A. Philippi's Zoological Notices. 



flagellum is vaulted exteriorly with a keel, interiorly grooved, 

 serrated and finely ciliated at the margins, so that they close 

 completely. The canal continues in the stalk (Stiel), but here 

 only the upper half is formed by the stalk, and is closed in- 

 feriorly by the scales of the outer antennae, as it seems the 

 upper lip divides the canal, which then proceeds right and left 

 to the branchiae. As far as I am aware, no similar formation 

 exists among the Crustacea. 



The feet are exactly as in the other species of Peneus ; all 

 have at the base a filamentary process corresponding to the 

 palpi of the foot-jaws ; the three first pair have pincers 

 (chela;), and increase from the first to the third in length, 

 which increase is effected, namely, by the growth of the tibia. 

 The fourth pair of feet is as long as the second, the fifth as 

 long as the third. The exterior foot-jaw is nearly twice as 

 long as the first pair of feet, and consists of rather cylindrical 

 and capillary joints. 



The figure PL IV. fig. 3. will render a more detailed de- 

 scription superfluous. 



Plate III. Fig. 12. Nauplius ciliatus, Phil. Sixty times magnified. 



a. Natural size. 

 Plate III. Fig. 13. Laophonte cornuta, Phil. Female, sixty times mag- 

 nified. 

 Plate IV. Fig. 1. Psamathe longicauda, Phil. Magnified sixty times. 



x. Natural size. 



a. The outer foot-jaw magnified 150 times. 

 Plate IV. Fig. 2. Thyone viridis, Phil. Examined with a power of sixty. 



a. Nat. size. 



b. The outer foot-jaw, with its palpus more strongly magnified. 



d. The second pair of antennae. 



e. The mandible, near it a foliaceous fringed organ similar to the 



one designated by g: should it be considered as branchia? 

 /. The one foot-jaw. 

 N.B. The maxillae could not be represented on this scale. 

 Plate IV. Fig. 3. Peneus sipkonoceros, Phil. Nat. size. 



a. Cross section of the tube formed by the flagella of the upper 

 antennae, magnified. 



6. Pontarachna punctulum^Vh.^xi Hydrachnidan of the Ocean. 

 (PI. IV. fig. 4. and 5.) 



Hitherto Hydrachnae have been found solely in fresh water, 

 but I have met with, and not at all unfrequently in the bay 

 of Naples, a spider belonging to this division of the Arachnida 

 likewise in sea-water. Unfortunately it is so minute, scarcely 

 ^rd of a line in length, that I have not been able to recog- 

 nise all its parts, although I have frequently examined several 

 specimens. The body is rather globular, anteriorly somewhat 

 acute, quite bare. Its colour is brownish-yellow, more fre- 



