1862.] HUXLEY STALK-EYED CRUSTACEAN. 421 



and apparently truncated in front, but deep behind, its postero-in- 

 ferior angle being somewhat produced, but rounded off. It measures 

 0*65 in. in extreme length, 0-3 in. in extreme depth. The dorsal 



Sketch of Pygocephalus (?) from the Coal-shale near Paisley, 



walls of the abdominal somites, of which only the anterior three or 

 four are clearly distinguishable from one another, are large in propor- 

 tion to the carapace, having a depth of 0*3 in., and an antero-posterior 

 length of 0-13 in. The free inferior edges are not clearly defined, 

 but their margins seem to have had much the same curvature as 

 those of Astacus or Homarus, The first obvious abdominal segment 

 is separated from the carapace by an interval, in which I thinli I 

 can trace the remains of the small, true, first abdominal segment, 

 not much more than half the size of the others. If this be the 

 case, then the dorsal parts of the fifth and sixth somites are broken 

 away ; and all that remains of the telson and the appendages of the 

 sixth somite is a broad flat plate, which lies in front of the third 

 and fourth abdominal somites. 



I explained in my previous paper the difficulties which I met 

 with in endeavouring to understand this part of the body of 

 Pygocephalus ; and I am sorry to say that the new specimen casts 

 but little light upon the subject. The appendages are fairly dis- 

 played. At the anterior part of the carapace I believe I can dis- 

 cern the eye-stalk, which is about 0*1 in. long, broader at its free 

 than at its attached end, and exhibits a depression, which is broad in 

 front, but narrows behind to a point on the outer side of its distal 

 half. This depression appears to result from the more yielding 

 character of the integument, that investing the rest of the eye-stalk 

 being dense and shining ; and the surface of this softer integument 

 is distinctly facetted. The character of the appendage, in short, 

 closely agrees with that of the dried eye-stalk of a Podophthal- 

 mous Crustacean. Behind and below the eye-stalk the remains 

 of the antennule are traceable ; and this is succeeded by the antenna, 

 its great basal scale being very largely developed. Behind these 

 follow about seven slender, filiform, jointed limbs, diminishing in 

 length from before backwards ; indistinct traces of a second division, 

 or exopodite, are discernible in these limbs. 



Notwithstanding the imperfect condition of this new specimen, 

 and the very little that it enables me to add to what Was already 

 known of Pygocephalus^ it is so desirable to call the attention of 



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