52 Psyche [April 



beyond it on the fourth vein. Abdomen very faintly greenish, cylindrical in middle, 

 the hypopygium small and concealed, not cutting into the fourth sternite at all. 



Length, 4.5 mm.; of wing 4.6. 



Female. Differs only in having the abdomen wider in the middle, and showing 

 a rather bright blue-green metallic color on the whole dorsal surface of the abdomen; 

 also in the larger size, 4.9 mm.; of wing 5.1. 



Forty-one specimens: Horse Neck Beach (type), Woods Hole, 

 New Bedford, Chelsea, Cohasset, Chatham, all in Massachusetts ; 

 Atlantic City, N. J. The Mass. specimens are dated from May 

 14 to Sept. 8, and were collected by Messrs. Johnson, Hough 

 and Melander. The New Jersey specimens are dated May 6, 

 and were collected by C. W. Johnson, who informs me that this 

 is the commonest salt marsh species. Professor Melander also 

 reports it extraordinarily abundant in salt marshes at Woods 

 Hole. 



I received this from Mr. Johnson under the name of viridiflos 

 Walker, but I do not see how it can be Walker's species. Walker's 

 description is mostly made up of items that would apply to almost 

 any kind of Hydrophorus, or in fact to many other flies; the 

 only character which seems of any diagnostic value is "wingribs 

 and poisers tawny; veins black, tawny at the base." I do not 

 understand the distinction between wingribs and veins, but 

 it seems clear that he was describing a species, of which there 

 are several, in which the basal part of the veins is yellow. This 

 character does not apply at all to the species here described. 

 It suggests cBituum to me much more than intentus, as Walker 

 mentions a length of 3mm. 



Hydrophorus cerutias Loew (figs. 1, 5). 



Male. Occiput bright green, with only one pair of post verticals; postorbitals 

 about eight on a side, extending down only about one third of the way to the 

 mouth; beard yellow or whitish, dense; cheeks not visible at all below the ej^es; 

 no black bristles under the neck; front yellowish or brownish pruinose; face long, 

 narrow above, wholly white pollinose, palpi concolorous and with rather long 

 pale hairs; antennse located rather high and pointing almost vertically upward; 

 all the joints elongated, but the third drawn out into a point along the upper edge 

 (see figure); arista short, the basal joint flattened so as to look like the tip of the 

 third antennal joint. Thorax quite bright green or bronze above, especially 

 bright behind; scutellum with only one small decussate pair of bristles, acrostichals 

 and dorsocentrals extremely small, humerals one medium and sometimes one small, 

 notopleural one; a tuft of pale hairs behind the humerus, above the suture; pro- 



