16 HYMENOPTERA. 



nearly hyaline for the rest, and in others almost uniformly fuscous. In size the 

 specimens vary from 18-24 millim. 



J 21. Ammophila gracilis. (Tab. I. figg. 7 ; 7a 9 <s.) 



Ammophila gracilis, Lepel. de St.-Fargeau, Hist. Nat. Ins., Hymen, ii. p. 381 \ 



Eab. Mexico 1 . 



Specimens from Mexico, from Presidio and Ven tanas (Forrer), and from Valladolid 

 in Yucatan (Gaumer), and from Panama, Volcan de Chiriqui (Champion), are possibly 

 referable to this species. 



They may be described thus :— Black ; the second joint of the petiole and the 

 greater part of the following segment red, lined with black above ; the face and cheeks, 

 the tubercles, an oblique line on the mesopleurse, and a spot on either side of the 

 median segment, clothed with a dense silvery pile ; the vertex and thorax covered with 

 rather long ashy pubescence. Head slightly punctured ; clypeus broadly rounded, 

 almost transverse in the centre. Ocelli hardly forming a triangle, and widely separated 

 from the eyes. Third antennal joint one quarter longer than the fourth. Prothorax 

 with a S -shaped furrow. Thorax rather strongly punctured ; scutellum longitudinally 

 striolated ; mesonotum with a broad furrow or depression in the centre and another 

 on either side ; a )-shaped furrow runs from the base and a straight one from the apex 

 of the tegulse; metanotum closely and finely transversely striated. Third cubital 

 cellule a little longer than the second at the top ; below it is about one fourth longer 

 than it is above. 



The male has the face more densely and widely silvery-pilose ; the oblique spot on 

 the mesopleurse is wider, and the pleurse and sternum are covered with rather long 

 dense greyish pubescence ; the hair on the head and thorax is longer and denser ; and 

 the clypeus is more projecting and more rounded at the apex. 



This insect is shorter than the species I have determined as A.fragilis ; the petiole 

 and the following segment are entirely red (and not black throughout above, while the 

 base of the petiole is red beneath) ; the pronotum has a furrow in the centre ; the 

 clypeus is more depressed inwardly at the apex ; the punctuation on the thorax is 

 closer ; the stigma is reddish ; and the third cubital cellule is only half the length of 

 the second above. 



A. azteca differs from it in having the apex of the clypeus transverse ; the clypeus 

 and cheeks without silvery pubescence ; the thorax more shining and less pubescent ; 

 the pronotum furrowed in the centre ; the furrow on the mesonotum wider and deeper; 

 and the wings distinctly fuscous-tinted throughout. 



J 22. Ammophila atriceps. 



Ammophila atriceps, Smith, Cat. Hymen. Ins. iv. p. 221 \ 

 Hdb. Mexico 1 . 



