1847.] Mropos Pvlsatorius. 195 



Tr TAR THUS. 

 iSAieW regularly semicircular; Jrc(7fi?//i 

 twice the length; medial lobe the wid- 

 est; litterul lobes with the base under 

 the shortest. 



Abdomen, medial lobe widest; lateral 

 segments curved and compound. 



Atops. 



Shield n smaller transverse segment; 

 breadth thrice the length; lubes equal 

 in width; lateral lobes approximately 

 equilateral. 



J bdomin, lobes equal in width; late- 

 ral segments transversely rectilinear. 



The characters here cited are deemed sufficient to establish two 

 species of trilobites upon the specimens under examination, the 

 point which the association desired to have determined; and if 

 the solution now offered is correct, Atops trilineatus remains a 

 fossil characteristic of the strata investigated by Prof. Emmons. 



Both specimens are quite flat, and the pressure having been 

 apparently nearly equal in each, this has not been taken into ac- 

 count in deciding the question of identity, for although the form 

 of the shield might have varied, the relative width of the lobes 

 would not have been materially altered. 



Future observation must determine how far these species may 

 approximate through their respective varieties. 



ATROPOS PULSATORIUS. 



BY THOMAS BARLOW. 



In looking over the " List of Noxious Insects " by Dr. A. Fitch, 

 in the September number of the Journal, I found an interesting 

 article on the subject of the death watch, [Jltropos pulsatorius.) 

 Dr. Fitch says, " Writers of the present day are not agreed wheth- 

 er the habit alluded to (of making a slight tapping noise like 

 the ticking of a watch) does belong to the present species, or not. 

 It is difficult to conceive it possible for so minute, so soft and 

 weak an insect, to produce any audible sound. A box, purposely 

 allowed to be much infested with these lice, has stood upon the 

 table beside me, and often less than two feet from my ear, during 

 the past season, yet no sound has ever been observed to issue 

 from it." 



The writer does not give an opinion whether he believes this 

 insect does or does not make the noise, but it is inferable from 

 what he says that he at least doubts the habit or ability. 



I have been aware for years that w^'iters attributed this noise 

 to this insect though as Dr. Fitch says, it was difficult for me to 

 conceive it possible, tor so fragile a thing to make an audible 

 soimd. I have many a time sought with great caution and perse- 



