30 



GROUP RELATIONSHIPS 



ostrohus are generally unisexual. In 

 this connection it is more pertinent to 

 discuss the few reports in which cones 

 of Sigillariostro'bus have been consider- 

 ed bisexual than the more numerous 

 records in which spores of one type only 

 (g-enerally megaspores) were reported. 

 Seldom has it been possible to prove the 

 unisexual nature of the cones conclus- 

 ively, although Bochenski (1936) dem- 

 onstrated that cones of Sigillariostrohus 

 czarnockii are undoubtedly unisexual. 

 It is probable that extensive use of sim- 

 ilar maceration methods will prove the 

 point more conclusively for other species. 

 In the meantime, the lack of substantial 

 reports of bisexual cones of Sigillarios- 

 trohus must be taken to suggest that 

 they are unisexual, particularly when 

 this is supported too by the indirect 

 evidence supplied by Mazocarpon oedip- 

 ternum. 



The fact that the ''microspores" men- 

 tioned by Schimper (1870) are actual- 

 ly quite typical megaspores has been 

 mentioned. The next suggestion of bi- 

 sexual cones of Sigillariostrohus is in a 

 paper by Kidston in 1897. In it he 

 illustrates a specimen identified as Sigil- 

 lariostrohus sp. (op. cit. 1897, pi. II, 

 fig. 1) which he thought might possess 

 microsporangia as well as megasporan- 

 gia. Only the megaspores are actually 

 demonstrated ; no microspores or con- 

 clusive evidence of microspores was ob- 

 tained from the purported microsporan- 

 gia, and the size of imprints of the 

 "microspores" are given as about 200 /x. 

 In the absence of other definite charac- 

 teristics, this seems too large for actual 

 microspores. The fragmentary cone, in 

 any event, is inadequate as a source of 

 definitive information. 



Miss LeClercq (1938) has recently as- 

 signed a cone from the Yorkian in Eng- 

 land, formerly identified mistakenly as 

 Sphenophyllostachys, to Sigillariostro- 

 hus sphenophylloides n. sp. This cone 

 is undoubtedly bisporangiate, as micro- 

 spores were isolated from the sporo- 

 phylls near the tip, and megaspores are 

 present throughout the basal part. It 

 is apparently slightly smaller than 

 Mazocarpon oedipiernum, and the sporo- 

 phylls are alternately arranged in seem- 

 ingly definite verticils, about ten per 



whorl. This verticillate arrangement is 

 apparently the feature which deter- 

 mined its classification under Sigillari- 

 ostrohus. No peduncle is present, and 

 Miss LeClercq describes the cone in her 

 diagnosis (op. cit. p. 168) as sessile. 

 From the specimen as it is illustrated 

 one cannot be sure that the cone was 

 actually sessile, but if it was it cannot 

 be placed in Sigillariostrohus but must 

 be placed in Lepidostrohus instead (see 

 discussion of peduncle on p. 26). With 

 the exception of its strict verticillate 

 phyllotaxy it conforms better with Lepi- 

 dostrohiis, and this character is by no 

 means diagnostic of Sigillariostrohus. 



Miss LeClercq (op. cit. p. 165, foot- 

 note) states that the ornamentation of 

 the megaspores of S. sphenophylloides 

 is distinctive and matches that of 

 Zerndt's type 14. Now the type 14 

 megaspores of Zerndt are quite variable 

 and surely comprise quite a group of 

 species (cf. Zerndt 1940, p. 148). Nearly 

 all would be classed in the aphanozonate 

 section of Triletes, (Schopf, 1938). 

 However, it does not seem that the 

 megaspores described by Miss LeClercq 

 actually have their closest alliance with 

 the type 14 megaspores of Zerndt or 

 with the ApJianozonati. The megaspore 

 she illustrates in proximal view on her 

 plate II, figure 2, seems to have a 

 tvpically folded lageniculate apex with 

 vestibule (cf. Schopf, 1938, p. 27). Al- 

 though a few of the spines on the ma- 

 cerated spore on her plate IV, figure 

 10, are short and stout, this is probably 

 due to chemical attack since others ap- 

 pear to be much longer, more slender, 

 and slightly sinuous, or curved. Miss 

 LeClercq indicates that the apiculae are 

 all the same size (op. cit., p. 165) and 

 also mentions that some of the spines 

 bifurcate, although she does not illus- 

 trate this feature. The megaspore coats 

 are imperfectly macerated but fairly 

 translucent, judging from her photo- 

 graphs taken by transmitted light. All 

 these characters (with the exception of 

 the bifurcate spines) are represented at 

 least partially in Triletes (Lagenicula) 

 kidstoni, in part, as described and il- 

 lustrated by Zerndt (1934, p. 26-27; cf. 

 pi. 28, figs. 2 and 3; and 1937, pi. 16, 



