SÉANCE DU 28 MAI 857 



a name without a description and figures nol heing usually accepted. 

 I do not agrée witli Professer Bonnier in placing Bopyrus alphei in the 

 genus Bopyrella, for I consider it a true Probopyrits, where I hâve 

 recently placed it, the abdomen of the female being segmented. My 

 figure is misleading, as it shows no segmentation, butât thetime it was 

 made 1 could not distinguish any segmentation in the spécimen at hand, 

 which was very transparent and colorless. Since receiving other spé- 

 cimens, I hâve been able to see distinctly the segmentation of the 

 abdomen. In Bopyrella, the abdominal segments are ail fused. 



During the short time that D"" Bonnier's work was in my possession, 

 I was not able to examine ail that it contains, but I noted the great 

 similarity of my genus Parapenœon to his genus Orbione. I do not, 

 however, consider my genus a synonym of Orbione^ for it dififers in 

 not having the sixth segment of the abdomen of the female produced 

 into pleural lamellse, that segment in Parapenœon being very small 

 and rounded. In the type species of Orbione the pleural of the sixth 

 segment lamellae are produced to such anextent thas theyreach beyond 

 the extremity of the uropoda. The second species oi Orbione, 0. incerta, 

 described by D"" Bonnier, dififers in this respect from the type species 

 and may come under my genus Parapenseon. The author suggests 

 that the second species of Orbione may represent a new genus. The 

 •female of Parapenseon agrées more with the female of Cryptione 

 Hansen than it does with the female of Orbione, but the maies in the 

 tow gênera are very unlike. When the maie of Orbione is known, 

 there may be other characters to differentiale Orbione from both Para- 

 penseon and Cryptione. At présent Parapenseon is quile as distinct 

 from Orbione as Orbione is from Cryptione. 



Urobopyrus Richardson is certainly very close to Palsegyge Giard and 

 Bonnier, but cannot be considered a synonym. In Urobopyrus " the 

 uropoda are a pair of double-branched appendages attached to the 

 terminal abdominal segment; the inner branches are smaller and more 

 slender than the outer branches ". Palsegyge has small, simple, rudimen- 

 lary knob-like uropoda, not lamellar in shape or elongated so as to 

 extend beyond the terminal segment, as is found in Urobopyrus. 



In speaking of the thoracic processes in Argeia as not being of epi- 

 meral origin, but arising from the posterior portion of the segment, 

 I made the statement that it was incorrect to refer to them as " lames 

 pleurales ". My idea was not to suggest that Giard and Bonnier had 

 confounded the " lames pleurales" with the " productions épimé- 

 riennes", but rather to point out that, in a strict sensé, it was not exact 

 to speak of them as " lames pleurales". They may be considered as 

 the posterior divisions of the " lames pleurales", thatview being now 

 generally accepted, the an terior division of the " lames pleurales" being 

 placed latéral to the ovarian bosses on the anterior portion of the seg- 



