136 MEMOIRS OF THE NATIONAL ACADEMY OP SCIENCES. 



details, which he has so faithfully drawn. I am inclined to think that the body was actually 

 broader than Dr. Kingsley has drawn it, and that tlie lateral spines of the carapace were visible 

 from above ; but I leave it as an open question. 



The carapace is of the same length as the urosome (abdomen) or slightly longer, being from 

 two-thirds to three-fourths as wide as it is long. It is very thin and delicate, and many specimens 

 have none. The sides are regularly curved, and unarmed behind the middle, but on the anterior 

 third are seven distinct, sharp lateral spines, the seventh being three times as large as the others 

 and situated on the anterior outer angle of the carapace. I cannot with certainty distinguish any 

 spines between this last-mentioned spine and the rostrum.* Casts of the latter are distinctly seen 

 in two specimens (Lacoe's 200/;^ and 200mm) to be small, triangular, short, and acute. The 

 rostrum itself is pretty well preserved in one specimen (Mr. Lacoe's No. 200^). It is rather long, 

 stout, strong, acute, situated between the first auteunse, and extending as far as the middle of the 

 third joint of the scape of the latter. In another specimen (Lacoe's 200oo, 200nn) the rostrum is 

 fairly well preserved ; it is long and slender, and about half as long as the carapace ; also as long 

 as the abdomen is wide in its narrowest part. 



In only a single specimen is a side view of an apparently folded carapace preserved. The 

 entire rostrum is long and straight, slender and acute, originating in the anterior third of the 

 carapace, the entire rostrum being about half as long as the carapace itself. (PI. VII, figs. 3. 3a.) 



Along the sides are numerous sharp spines. Whether there was, as in the other form (A. 

 grossarti), a series of dorsal spines our specimens do not distinctly show. Behind the base of the 

 rostrum a median ridge extends to the posterior edge of the carapace. The lower edge of the 

 carapace is serrate on the anterior third, as in all the other specimens. On the surface of the 

 carapace an apparently false or superficial suture passes out laterally from the anterior third, and 

 another impressed line, better marked, from the posterior third, extending half-way to the edge 

 of the carapace. The surface of the carapace is seen to be finely shagreened, but scarcely tuber- 

 culated, as iu the European A. grossarti. 



Of eyes no traces are visible in any of the specimens except one, and I am inclined to the 

 opinion that they were either wanting or very small, and concealed under the front edge of the 

 carapace. At the same time it should be observed that in none of the fossil macrurous Crustacea 

 from the Carboniferous are the eyes preserved. It may also be borne in mind that in the deep- 

 sea Penlacheles scnl])li(s S nith no corneal area was to be detected, and in Willemcesia and the fossil 

 Eryoniscus the eyes are entirely wanting.! So far as we can decide, the front edge of the carapace 

 is not excavated at the point wliere we should look for eyes or eye-stalks, but, on the contrary, 

 seems to be quite regularly convex. Still, additional specimens are needed to clear up the exact 

 nature of the front edge of the carapace. 



In most of the specimens the thin, delicate carapace has not been preserved. When it ife 

 absent the five thoracic segments are distinctly marked, of about the same length. In front of 

 these are three cephalic segments, making eight segments in all apparent iu some specimens. 



The first anteunre are large and long ; the scape three jointed, first joint long, the second about 

 one-half as long as the first and of about the same width; third joint a little longer, but smaller, 

 than the second; the two flagella are a little longer than the scape, the inner one about half as 

 thick and evidently only half as long as the outer one. (Lacue, No. 200y.) 



The second antennie are, with the sca[)e, considerably stouter than those of the first pair; first 

 joint short and stout, but longer than broad ; second very short, oblique at the end, and consid- 

 erably shorter than the third joint, which is about as long as tliick; the flagellum is very long and 

 slender, multiarticulate, at least as long as the carapace, and directed backward, as in Pentacheles; 

 there is an antennal scale present, but its outlines are very indisfinct. 



The five pairs of legs are preserved (Nos. 200/y>, 200"""); tliey are all of nearly equal size, the 

 first pair apparently being no larger than the others, in this respect dift'ering from Galathea and the 

 existing Galatheidea. Of the first pair of limbs there are iu one specimen (200d) traces of nearly 



■ Dr. Kingsley li.is, bowtiver, detected a spiue at this point and iuscrted it iu his drawings, as seen in the plate. 



t After this paper was written the specimens were sent to Dr. Kingsley to be drawn ; among them the specimen 

 with traces of an eye. He has drawn iu the eye ; and on examining the specimen again, I thinli that he is right iu 

 representing the eyes. It was apparently large and well developed. 



