188 PROCEEDINGS OF THE ACADEMY OF [March, 



wide shallow cavity tomentose in the bottom, and small spreading 

 and reflexed generally persistent lobes; flesh thin, hard, acid, greenish 

 yellow; nutlets usually 4, broad and rounded at the apex, gradually 

 narrowed to the rounded base, ridged on the back, with a low narrow 

 or broad grooved ridge, 7.5-8 mm. long and 4-4.5 mm. wide. 



A shrub 4-5 m. high, with a stem 7-10 cm. in diameter, covered 

 with dark brown bark separating into large loosely attached scales, 

 and stout nearly straight glabrous branchlets dark orange-green and 

 marked by pale lenticels when they first appear, becoming light 

 chestnut brown and very lustrous in their first season and dull gray- 

 brown the following year, and armed with numerous stout straight 

 or slightly curved chestnut brown shining spines 3-4.5 cm. long and 

 compound and very numerous on old stems. 



Banks of rocky ravines, between Carnot and Stoop Ferry, Alle- 

 gheny County, O. E. Jennings, (Nos. 74 type and 75) May 20, 1907, 

 O. E. and Grace K. Jennings and B. H. Smith, October 6, 1907. 



4. Medioxim.e n. gr. 



Leaves thick, hairy on the upper surface early in the season, glabrous 

 and usually smooth at maturity; petioles long and slender. 

 Flowers in few-flowered glabrous corymbs; stamens 10 or less; 

 anthers rose color or rarely pink. Fruit subglobose to short- 

 oblong, ovate or obovate, generally longer than broad, rarely 

 slightly angled, scarlet, crimson or orange-red, occasionally 

 slightly pruinose, ripening late in September or in October; flesh 

 hard and solid; mature calyx sessile; nutlets 2-5, usually 3 or 4. 



In this group I have placed a number of shrubby species which 

 in some important characters appear intermediate between the Prui- 

 nosae and the Tenuifoliae. From the former they differ in their thinner 

 leaves, smaller flowers, always glabrous usually few-flowered corymbs, 

 generally fewer stamens with rose-colored or pink anthers, and especially 

 in the fruit ; this has a sessile calyx, is rarely slightly pruinose, never 

 green at maturity like that of many of the Pruinosae and generally 

 ripens earlier. From the Tenuifolise the plants of this group differ 

 in their thicker leaves, generally fewer-flowered corymbs, and in their 

 solid not succulent later-ripening fruit. In addition to the species 

 enumerated in this paper, Crataegus alacris Sarg. and Crataegus vittata 

 Ashe of eastern Pennsylvania may be placed in this group, as well 

 as many of the well-known species of western New York, Ontario and 

 Michigan which have been grouped with the Pruinosae, like C. opulens 

 Sarg., C. maineana Sarg., C. diffusa Sarg., C. compta Sarg., C. dissona 

 Sarg., and others. 



