394 PROCEEDINGS OP THE ACADEMY OF 



Early in the summer of 1860 I sent a single $ vastus along with a J 1 frater- 

 nus, to Dr. Hagen, supposing them to be identical. In his reply he kindly 

 pointed out three of the principal distinguishing characters, and informed me that 

 he had received from Maryland another $> of the same species,which he had 

 named vastus the J 1 being to this day, I presume, unknown to him. In a sub- 

 sequent letter he said that " vastus was probably a new species." It will be 

 noticed that vastus is not included in the Synopsis. The reason I do not know ; 

 but I conjecture, from collating the description of 9 Gomphus vulgatissimus, 

 that until the discovery of $ vastus, it was difficult or impossible either to se- 

 parate the American species from its European prototype, or to identify the two 

 species satisfactorily. To Dr. Hagen, therefore, justly belongs the honor of 

 attaching his name to this fine and interesting insect; to me belongs only the 

 labor of describing it from an unusually large number of specimens. 



Gomphus graslinellus, n. sp. ^ 9 Differ from G. f rater nus only as follows : 

 the posterior prothoracic lobe is black, generally with a central yellow dot ; 

 the carina of the dorsum of the thorax is black ; the eighth abdominal segment 

 is yellow on the lateral margin for its entire length, and the tibiae are exteriorly 

 yeilow, except at the tip. In the $ the sheath (gaine) of the penis is conspicu- 

 ously pruinose; and the superior abdominal appendages have a small inferior 

 tooth very near the tip, and in addition a very large quadrangular one on the 

 middle of their external side, as in the European G. graslini. (Mon. Gompb., 

 Plate viii., fig. 3.) In the $ there is no lateral thorn on the carina of the ver- 

 tex, and the vulvar scales are only one-sixth as long as the ninth ventral seg- 

 ment, and divaricate from their base. 



Length tf 5053 mill. ; $ 5153. Expanse J> 6669; $ 66 TO. Ptero- 

 stigma 3 J 4 mill. Four J>, seven 9 . Occurred in Coal Valley Creek, in 

 Rock Island County, and also on the Des Plaines and Chicago rivers in Cook 

 County. Its European representative, G. graslini, has black markings on the 

 front, the carina of the thoracic dorsum yellow, and two yellow vitta? (anterior 

 and posterior?) on the outside of all the thighs, whereas graslinellus, like /rater- 

 nus, has only a posterior yellow vitta on the anterior femora. 



Gomphus fluvialis, n. sp. J* Obscure greenish yellow. Headwith the occi- 

 put straight, narrowly margined on its sides before and behind with black, and 

 with long, black ciliations ; vertical vesicle black, cariniform, abbreviated, 

 transverse', emarginate, slightly tubercled at each extremity ; antenna?, and the 

 whole region of the ocelli to the base of the occiput, black ; seta of antennae 

 generally pale at tip ; front sharply and squarely angulated, ot as prominent 

 as in fraternus, with its upper side basally fasciate with palish brown, the an- 

 terior edge of the fascia widely biemarginate ; anterior surface of front with its 

 upper half and its two transverse foveae, generally palish brown, and its infe- 

 rior corners brown ; epistoma clouded with brown ; labrum anteriorly margined 

 with brown and with a brown vitta; extreme tips of mandibles, and the termi- 

 nal processes of the lateral labial lobes, pale brown; back part of the head 

 brown next the occiput. Prothorax brown black, anteriorly and laterally 

 yellow, and uniformly with a double yellow spot immediately before its 

 posterior lobe. Dorsum of the thorax with the dorsal carina, which is not 

 higher than usual, always brown black from its bifurcation backwards, gene- 

 rally in front of the bifurcation brown black except its extreme edge above; a 

 double, central, brown-black, wedge-shaped stripe, not attaining the anterior 

 edge by a third or half millimetre, and narrowly confluent before and behind 

 with the antehumeral, occasionally not confluent before; a wide brown black 



of anv such appendage. I suspect that I am the first to announce it as a normal, or perhaps only 

 S sexual character of the great genus So^s. At ^TCo^Me^ll 

 is enumerated in the list of the sexual distinctions of that genus in the " Monograpbie, tf."J 

 SimUar sexual appendages on the head are elsewhere in the Class Insecta (genuma). so far as 1 

 Sleet at pwse" found not on the ? but on the d head, as in the well-known coleopterous 

 Phanmus carnifex and many other lamellicorn species. fSpnr 



