DINANAMESUS SPANIUS 213 



This species is closely allied to Dinomimetes epitedeus. The cerci of the 

 female are the same, lacking the two terminal filaments of the other species. It 

 differs in the lack of setae on the postnotum (not a strong character, apparently) 

 and in the proportionate lengths of the joints of the female antennae. The 

 female of Dinomimetes epitedeus has acquired antenna constructed essentially 

 like those of the male, while that of the Deinocerites pseudes retains the usual 

 female type, characteristic of the other species of Deinocerites. Our specimens 

 from the east coast of Mexico are smaller and paler than the others, those from 

 Tampico (our northernmost locality) being the smallest, but we have been 

 unable to find any specific differences and consider this a somewhat widely dis- 

 tributed form with slight local variability. 



Genus DINANAMESUS Dyar & Knab. 

 Dinanamesus Dyar & Knab, Smiths. Misc. Colls., quart, iss., lii, 259, 1909. 



The type species of Dinanamesus Dyar & Knab is Dinanamesus spanius Dyar 



& Knab. 



Generic Diagnosis of Adult: 



Palpi short in both sexes. Antennae long and slender, similar in the sexes, the 

 female with second joint about eight times as long as wide, third and fourth together 

 longer than second, last joint slender; of the male the second joint about nine times 

 as long as wide, the third nearly as long as the second, the succeeding joints subequal, 

 the terminal joint enlarged into a slight knob; hairs of whorls rather short and 

 sparse in both sexes, slightly longer in the male than in the female. Prothoracic 

 lobes remote dorsally. Mesonotum with longitudinal rows of coarse setae. Post- 

 notum nude. Abdomen of female compressed, truncate at tip; that of male somewhat 

 expanded at tip, with stout claspers. Legs rather long and slender, the claws simple 

 in the female. 



No larvas are known in this genus. 



The larvEe live in the water in holes formed by certain species of crabs along 

 the coast ; we have no specimens as yet. The adults inhabit the upper part of 

 the crab-holes. 



Panama. 



The genus Dinanamesus, while clearly belonging to the deinoceritines, ex- 

 hibits a transition toward the culicine forms. It is probably the lowest, least 

 specialized, member of the group, in which the peculiar adaptations of the 

 antennas are but slightly developed. These crab-hole inhabiting species possess 

 peculiarly developed antennas in order, as we suppose, to enable them to detect 

 the approach of their crustacean host and fly out of the holes before being over- 

 whelmed in the water in the bottom by the incursion of the crab, whose body 

 must completely fill the entrance to the hole. Other mosquitoes inhabiting 

 these holes, such as Culex latisquama, have similarly modified antennae, al- 

 though in a much less degree, evidently exhibiting a common adaptation to a 

 common need. 



But a single species is known. 



DINANAMESUS SPANIUS Dyar & Knab. 



Dinanamesus spanius Dyar & Knab, Smiths. Misc. Colls., quart, iss., lii, 259, 1909. 

 Oeiginal Desceiption of Dinanamesus spanius: 



Fe:male. Proboscis rather long and stout, black-scaled. Occiput dark-scaled, the 

 margins of the eyes white. Mesonotum brown-scaled, with numerous coarse dark 

 bristles, particularly in the antescutellar region and at the bases of the wings. 

 Abdomen somewhat compressed towards the tip, blunt, the cerci small, vestiture 

 above brown v/ith bronzy luster, beneath paler; tip of the abdomen coarsely hairy. 

 Wings hyaline, the scales of the veins brown, long, narrowly ovate to ligulate; those 

 of the costa with a strong bronzy luster. Legs with the tibiae rather short and stout, 



