15 



rare and evidently archaic ant, secure additional specimens, 

 especially of the unknown male and female, and investigate 

 its habits. 



Genus Myrmecorhynchus, Ern. Andre. 

 Worker. Polymorphic, presenting distinct maxima, 

 media, and minima forms, differing especially in the size and 

 shape of the head. Worker maxima with the head large and 

 broad, with large elliptical, feebly-convex eyes, placed near 

 the middle of its sides but on the dorsal surface. Mandibles 

 triangular, very convex, with numerous, rather crowded, 

 acute teeth on the apical border. Palpi short ; maxillary pair 

 6-jointed, labial pair 4-jointed. Clypeus large, trapezoidal, 

 not extending back between the antennal insertions or frontal 

 carinae, with an anterior projecting, median lobe. Frontal 

 area large, distinct, triangular. Frontal carinae short, nar- 

 row, diverging behind, not concealing the insertions of the 

 antennae, which are very near the posterior clypeal border 

 and the anterior ends of the frontal carinae. Frontal groove 

 distinct. Ocelli small, but well developed. Clypeal and 

 antennal foveae confluent. Antennae 12-jointed. Funiculi 

 gradually enlarged towards the tip, with the five terminal 

 joints forming an indistinct club. In the minima the head 

 is much narrower, the eyes more prominent and proportion- 

 ally larger and situated more on the sides of the head, the 

 clypeal lobe is much more projecting, the mandibles much 

 more elongate with straight lateral borders, less convex dorsal 

 surfaces, and more numerous teeth. The ocelli and frontal 

 groove are absent, the antennae more slender. The media is 

 intermediate in the shape of the head between the maxima 

 and minima, the frontal groove is feeble, and the ocelli are 

 minute or indicated by pits. All three forms have the thorax, 

 petiole, and gaster of essentially the same shape. Thorax 

 rather small and narrow, scarcely longer than the head, 

 including the mandibles, with deep and rather long meso- 

 epinotal constriction, with distinct promesonotal suture and 

 the mesonotum bounded behind by a distinct suture separated 

 by a space from the anterior suture of the epinotum. In this 

 space, representing the metanotum, lie the metathoracic 

 spiracles, which are produced and distinctly tubular, especi- 

 ally in the media. Epinotum rounded and unarmed. Petiole 

 with well-developed, erect, bluntly rounded scale. Gaster 

 voluminous, its first segment smaller than the second and 

 third, which are subequal : the constrictions between the seg- 

 ments well marked. Anal orifice surrounded by a circlet of 

 cilia. Middle and hind tibiae with short but distinct spurs; 

 tarsi with well-developed, rather straight, simple claws. Pro- 

 ventriculus (fig. 2) small and very short, the bulb scarcely 



