SPECIFIC RELATIONSHIPS 



33 



g'uisliing SigiUariostrohus from Mazo- 

 carpon are notably absent. In large 

 part, therefore, the distinction between 

 the groups is probably artificial in that 

 the chief distinction is not based on 

 heritable characteristics but on differ- 

 ences in preservation which prohibit a 

 comparison of critical features. The 

 demonstrable presence of intrasporan- 

 gial tissue in Mazocarpon is the only 

 outstanding criterion not known from 

 Sigillariostrohus. Bochenski (1936) 

 mentions that the megaspores of S. czar- 

 nockii occasionally bear a faint reticu- 

 late imprint. This may be due to a 

 ''ramental" remnant of intrasporangial 

 tissue as in the case of spores of M. 

 oedipternum, (p. 17) and if so it is the 

 first record of such tissue from compres- 

 sion fossils. If exact correlative rela- 

 tionship is ever proved between these 

 two genera, abundant evidence of this 

 sort must be sought. In the meantime 

 the basic information relating to the 

 sigillarians seems to be more clearly in- 

 dicated if the present grouping is main- 

 tained. The likelihood is that these 

 genera could be merged for specimens 

 of Pennsylvanian age without violating 

 any phylogenetic concepts. In the 

 earlier history of the sigillarian alliance, 

 difficulties in interpretation are bound 

 to arise that will hinge on definition of 

 the genera. It will probably simplify 

 the problems if nomenclature is applied 

 strictly, even though this results in the 

 same biological group being generally 

 represented under several generic terms 

 recognized as partially synonymous. 



SPECIFIC RELATIONSHIPS 



There are no available records of 

 Sigillariostrohus in any beds adjacent 

 to the Calhoun horizon in Illinois. Cones 

 of Mazocarpon oedipternum should be 

 easily recognized in impressions or com- 

 pressions by the unique character of 

 lamina and dorsal heel of sporophylls, 

 and later investigation may disclose 

 them. Lepidophyllum drevifolium Les- 

 quereux (1858) and the allied form, 

 L. minutifolium Lesquereux (1884), ap- 

 pear to have similar very short laminae, 



but other information is lacking and a 

 close relationship is dubious. Both of 

 Lesquereux 's species are recorded from 

 appreciably lower Pennsylvanian hori- 

 zons. 



The Sigillariostrohus cone, designated 

 as Lycopodites lacoei by Lesquereux 

 (1884, p. 780), is from Oliphant No. 1 

 bed in the anthracite field of Pennsyl- 

 vania, of about middle Conemaugh age. 

 It seems to be nearer to the age of the 

 Calhoun horizon than other forms of 

 Sigillariostrohus. The sporophylls of 

 '' Lycopodites" lacoei are longer than 

 those of Mazocarpon oedipternum, and 

 more numerous sporophylls seem to be 

 present in each whorl. The spores are 

 unknown, but in Lesquereux' drawing 

 (op. cit., pi. CVII, fig. 1) the sporangia 

 appear relatively tumid and somewhat 

 similar to those of Mazocarpon. How- 

 ever close the generic affinity between 

 Mazocarpon and Sigillariostrohus may 

 be, there seems no close specific rela- 

 tionship between M. oedipternum and 

 species of either Mazocarpon or Sigil- 

 lariostrohus, at least so far as the gen- 

 eral size and form of the sporophyll 

 allows us to judge. 



Mazocarpon shorense, on the other 

 hand, appears to be more closely related 

 to certain species of Sigillariostrohus 

 than to either the older species, Mazo- 

 carpon pettycurense, or to M. oedipter- 

 num. In length the M. shorense sporo- 

 phyll laminae seem to be about the same 

 as in Sigillariostrohus ciliatus Kidston, 

 >S^. czarnockii Bochenski, and ;S^. gothani 

 Bode. The latter two species are dis- 

 tinct from M. shorense in that they both 

 appear to have levigate megaspores, and 

 also they are both geologically younger 

 than M. shorense. The megaspores and 

 other details of Sigillariostrohus cilia- 

 tus are in closer agreement with M. 

 shorense and they are probably rather 

 closely related. There is, of course, no 

 adequate basis for considering them 

 specifically identical. Sigillariostrohus 

 czarnockii and ^S'. gothani appear closely 

 related to each other although the in- 

 formation available for S. gothani is 



