386 TWENTIETH REPORT ON THE STATE CABINET. 



" much narrower anteriorly, and it continually tapers backwards instead of 

 "widening. The pleurse also differ." 



It would appear from the language here used, taken in connexion with 

 the paragraph 4, that I had identified Ldchas pugnax with L. breviceps ? 

 while in fact it is Prof. Winchell who has made the identification. Nor 

 do I regard the " glabella [of L. pugnax] as extremely similar to that of 

 L. hreviceps, but as very distinct from it ; and I should never have thought 

 of making the comparison, except to point out these marked differences. 

 The comparison with tlie pygidiura is equally wide of the mark ; for I do 

 not see how it can be said that the axis of the pygidium of L. breviceps 

 widens posteriorly, any more than that of any other species of the genus. 



In his remarks on page 104, Prof. W. compares L. pugnax to L. nereuSj 

 a very distinct form. How it is to be distinguished by the '^' want of artum- 

 lations in the peripheral area of the caudal shield,'^'' I do not understand; 

 since the lateral lobes of the pygidium of both species are marked by the 

 sutural and intercostal furrows, as is clearly shown in the figure of Prof. W, 

 and that of Yol. 2, Pal. N. Y. The same remarks seem to me applicable to 

 what Prof. W. terras the "similar flat inarticulated flap " of L. canadensis. 

 Since Prof. Winchell has not illustrated the pleura of his species, and 

 I have not seen any of these parts in connexion with the specimens 

 obtained either in Wisconsin, or at Bridgeport, I am not prepared to speak 

 of their similarity or diflerence. 



Lichas pugnnx is apparently a well-marked and distinct species, though 

 the pygidium is very incorrectly represented in the figure. The glabella is, 

 in all respects, very similar to that of Lichas boltoni. 



" (c). Pterinea volans^ W. & M. ; with Avicula emacerata, Conrad. Had 

 " Prof. Hall seen the fall-grown and perfect specimens in our possession^ 

 '*it is doubtful whether this identification would have been made." This 

 is scarcely clear ; but I understand Prof. Winchell to mean that he has 

 identified Pterinea volans, W. & M., with specimens regarded by me as 

 A. einacerata, Conrad. The specimens communicated under this name 

 (P. volans) by Prof. Winchell are not identical with those regarded by 

 me as A. emacerata, but appear to me more nearly identical with 

 P. stricBcosta, M'Chesney. 



"(^)." Subulites brevis, W. & M., may prove a distinct species. Should 

 the want of symmetry be found a constant feature, the specific distinction 

 should be maintained. 



" 5. The following six new genera and species, described by Prof. Hall, 

 " have been identified by us wdth established forms." [There are two new 

 genera proposed, and five species as new.] 



" (a). Ambonychia aphei with A. mi/tiloidea, Hall.''^ Ambonychia aphea 

 is distinct from A. mytiloides ; but I have been in error in citing A. acuti- 

 rostra (See Addenda). 



