TIM I." "'' 



nn.U 1 



;-.. i lullin.- cif hi-;i<l "f ///.i MUJ) rrawtdiiKfii Wthlenl-Ttf, vi< wed frmn In front 



I>r. Kmmon- in M'J noticed, under the ii;iine lllnmis tr?n1n< .</-, a .-mall IlitmaaitU 

 from the Trenton limestone at Watertown. N . "> . LM\ ing ;i profile and dorsal view of 

 a -ingle entire -prcimen. Tlif-e tL'inv- .in- here introduced. In the same place he 

 a figure o| a much larger ami quite distinct species, from pre.-umalily the same 

 hnri/iiM. referring to it liy the name Himnix/u* tnntonrnsi*. This use of the same 

 -pecitic naiiu' for ipedet evidently di-tinct. and \\liich the author regarded a?- 

 generically ditlen-nt. ha- l>een tlic -ourcc of tht> 'onfiision of the two. ll/m<- 

 tr< M/o;i7i.v/x Kmmoii-. ha- not IHMMI n-cn^iii/i'd liy later writers; litnuusfMit frrntonensis 

 Kmmons was reforred liy Hall (/<> . '-it.) to IH<inns. \vliili> Kminons' llltrnus trentontnsis 

 was not noticed l>y this writer. This involution of names is the probable cause of 

 both of Kmmons' forms being referred to /. trentonen.ii* in the catalogues of Miller 

 and Vogdes. 



The Ilumastiix tr> n/<i> usi* Kmmon- i /. 'i-i-ndinfnsi* Hall), as represented in the 

 original figure, is a large species with /////;w.---like cephalon and broadly lobed thorax 

 and pyjridimn. The longitudinal loliation is so pronounced, and the median lobe 

 of the body so narrow, as to make the reference of the species to Rumastus 

 iiicon^ruon-. It appears from the description of this species given by Mr. Hall (loc. 



that the original specimen was lost, and that his account, as well as his figure 

 of it, was drawn from a plaster cast. One or the other of these figures must have 

 been quite inaccurate, for the latter represents a fossil in which the lobation is 



Aether obsolete, except for the faint evidences of dorsal furrows upon the 

 cephalon. The animal. uted thus, would he an excellent Rumnttus. I am 



-. 30. 31. B<inuut< . Ooplef th- nftfinal flt-iircs of the specie*. 



disposed to believe the original figure the more n-Iialde: it i- certainly the more 

 natural in appearance, and was executed hy Mr. ! it Kmmons. jr., whose 



skill as a delineator of fo il- i- widely and favorably known. We may safely 

 leave to th. ; ie name lUirnu* /> .ind -hall then-fore revive for 



