Prosopistoma of Latrellle. 193 



he has misdrawn by making its posterior lateral angles 

 extend outwards. The preceding space on each side of 

 the pointed metasternum is regarded by M. Joly in all 

 his articles as abdominal, and is actually lettered C 1, 

 C 2, C 3, and C 4, as so many abdominal segments, 

 respecting which I can only observe that in both spe- 

 cies I have failed to see any trace of articulation exce])t 

 that between C 4 and C 5, as above mentioned. M, Joly 

 further represents, in the middle of the hind margin of 

 his C 5, a small tongue-like piece, which he describes 

 as "les deux valves a travers 1' orifice desquelles s'echappe 

 I'eau qui a baigue les fansses branchies." I have seen 

 nothing of these valves. The terminal part of the body 

 in all the specimens before me consists of three segments, 

 the first and second of which are very short, with the 

 lateral posterior angles produced to a point, and the 

 third is large, with the anterior and lateral margins raised 

 with a sharp edge, giving the appearance of a basal 

 division, which M. Joly has enlarged into a distinct 

 segment, making the merely rounded and slightly con- 

 cave portion of the segment quite distinct from the other 

 part, with its posterior edge scalloped,* and with a circu- 

 lar opening in the centre, which he terms the " ouver- 

 ture anal." In all my specimens the hinder margin is 

 entire and sharp, and the upper surface without any 

 aperture. 



In none of my specimens is there to be seen any trace 

 of the three anal filaments which M. Joly represents as 

 nearly the third of the length of the entire body. 



The Avant of sufficient materials has prevented me from 

 instituting an examination of the structure of the mouth 

 organs or of the respiratory apparatus as figured by 

 M. E. Joly. 



He represents the labrum as transverse and ciliated, 

 with the anterior lateral angles rounded off, and the middle 

 of the fore margin slightly produced (his fig. 5); the man- 

 dibles (fig. 7) and maxilla3 (fig. 8) as elongated, terminating 

 in several sharp teeth (the maxilke having an extra and 

 stronger bifid tooth), below Avhich are a few strong curved 

 bristles, and the lower lip (fig. 6) as emarginated at the 

 sides, and rounded in front with two small palpi, having 



* In his moi'e recent fignres, I\I. Joly lias vopresentcd the extremity of 

 his 4th abiloniinal scgnu iit as truncate, with tUiec ridges produced by the 

 bases of the three anal iilanicuts. 



