460 BENNETTITALES [CH. 



concrescent portion of the whorl of microsporophylls and by the 

 ten short free lobes which bear two rows of lateral synangia 

 (fig. 565, C). Among the British forms Williamsonia whitbiensis 

 would appear to be the most closely allied type. W. mexicana 

 occurs in association with Otozamites fronds, as is the case with 

 an Italian specimen figured by Zigno 1 , but in the Mexican species 

 there is no conclusive evidence of organic connexion. 



OTHER SPECIES OF WILLIAMSONIA. 

 Williamsonia Haydeni Seward. 



A Jurassic species from Afghanistan 2 founded on a single 

 specimen of a flattened broadly-oval flower similar to W. gigas 

 but smaller and enclosed by narrow linear bracts. An interesting 

 feature is the occurrence of a funnel-shaped depression at the 

 apex showing radiating lines on its surface as in the Williamsonia 

 represented in fig. 546, A. In all probability these lines denote the 

 persistence of a collar of interseminal scales on the upper part of 

 the elongated conical receptacle. An examination of the carbona- 

 ceous material revealed the presence of some short rods agreeing 

 in size and shape with the interseminal scales of other species. 



Williamsonia Otozamitis (Zigno). 



Zigno 3 instituted the generic name Blastolepis for some speci- 

 mens from the Jurassic rocks of north Italy which he referred 

 to three species, B. falcata, B. acuminata, and B. Otozamitis. 

 These are true Williamsonias closely allied to W. gigas. An 

 examination of the type-specimen of B. Otozamitis in the Padua 

 collection led me to the conclusion that Zigno was correct in 

 representing the ovulate strobilus, which shows an annular area 

 like that in specimens of W. gigas, as being in organic connexion 

 with an Otozamites frond. Wieland has recently discovered species 

 of Williamsonia in Mexico that he correlates with Otozamites leaves. 



Williamsonia sp. Seward. 



Though by no means satisfactory as a trustworthy record of 

 the genus, the specimens so designated from the Kimmeridgian 

 of Scotland 4 are probably imperfect examples of the genus. 



1 Zigno (85) PI. XLII. 2 Seward (12) p. 26, PI. m. fig. 44; PI. vn. fig. 86. 



3 Zigno (85) p. 173, PL XLII. figs. 911. 



4 Seward (II 2 ) p. 691, PL v. fig. 99. 



