HACKBERRY GALLS, 613 



a large egg of some diurnal Lepidopteron; short, conical, or subglobu- 

 lar in outline, arising from a circular, truncate base, rounded off at tip 

 where it is furnished with a short spine or nipple; surface dark green, 

 opaque, granulose, usually with faint and shallow longitudinal furrows 

 and usually hirsute with short stout hairs; sides at the base with more 

 or less distiuct, irregular protuberances. The gall is not entirely sessile, 

 but only connected with the twig at the central part of its base. A 

 vertical section shows a single spherical cell (rarely two) having a 

 thick whitish-yellow, hard and woody wall. Average height of gall 4^^ 

 (excluding the apical spine); average diameter at base 3.4"''\ The gall 

 varies in shape, some specimens being more conical, others nearly glob- 

 ular or even slightly depressed at tip, while others are not hairy and 

 less opaque, the surface being covered with little pustules. The latter 

 form possibly constitutes a distinct species. 



31. Cecidomyidous galls on the tender twigs occurring either singly 

 or in groups of two, three, four or more specimens ; rarely, also, singly on 

 the under side or even the upper side of the leaf. The gall bears a close 

 resemblance to the winged seed-capsule (achenium) of a Runiex, but the 

 wings vary in number from three to five and are often irregularly devel- 

 oped, while the tip always ends in a long curved spine. The wings termi- 

 nate in a sharp ridge which is sometimes double. Gall opaque, not 

 hairy, sculpture consisting of faint and irregular 'transverse stride ; color 

 pale yellowish-green, at apical third usually of a more decided green 

 and darker. A longitudinal section reveals a single large, regularly 

 ovoid cell surrounded by a thin hard wall. Average height of gall 4.5""™, 

 excluding the apical spine ; generally as wide as high ; length of apical 

 spine variable, but usually a little more than half the height of the gall. 



This gall is easily recognized from its peculiar form. 



32. Cecidomyidous galls on the under side of the leaf, always arising 

 from one of the principal leaf-veins, occurring usually singly, rarelj' in 

 pairs. In form, sculpture, and pubescence the gall bears a most strik- 

 ing resemblance to that produced by Pachypsylla celtidis-puhescens (see 

 p. 619) but it is much larger, more globular, and at once distinguished by 

 the absence of the cupuliforui depression on the upper side of the leaf 

 which is so characteristic of many Pachypsylla galls. A vertical cut 

 through the gall shows a relatively small ovoid cell surrounded by a 

 thick, hard yellowish-white wall. On detaching the gall the base is seen 

 to be truncate and attached to the rib of the leaf by an extremely short 

 conical style which is not visible from the sides. Average height 3.5™™ ; 

 diameter at middle, 3.5™™ to 4™™. 



33. Cecidomyidous galls on the under side of the leaf arising from the 

 leaf-ribs, occurring either singly or in smaller or larger groups. Gall 

 rosette-shaped, re'sembling the seed-capsule of certain Malvaceous 

 plants of the genus Hibiscus, circular in outline, greatly flattened on 

 the top and here furnished with a short central spine or median nijjple 

 (frequently broken off); sides sulcate, with from ten to twelve more or 



