CYSTOSPORITES 



41 



half a millimeter in diameter to more than 

 twice that. Smallest forms are more 

 nearly isodiametric becoming axially elon- 

 gate with increased size. When compressed 

 both abortive and fertile members are 

 folded irregularly ; their longest axis is 

 generally least effected. 



Ornamentation, — Generally absent; 

 abortive forms may show apparent re- 

 ticulation. 



Haptotypic features. — Strongly devel- 

 oped in fertile forms but relatively in- 

 conspicuous because of the enormous ex- 

 pansion of the distal part of the spore 

 body. Sutures definite, extended to the 

 arcuate ridges which are strongly thick- 

 ened, lips often moderately defined; py- 

 ramic areas distinct from adjacent spore 

 coat. Apex may be somewhat elongate. 

 On smaller abortive forms haptotypic 

 features are commonly masked by develop- 

 ment of a thick rugose, more or less 

 triangular cushion which effectively seals 

 the spore apex. Arcuate ridges are in- 

 conspicuous but sometimes their termini 

 are weakly defined adjoining the corners 

 of the cushion. Larger abortive forms 

 commonly show haptotypic features more 

 like fertile spores but somewhat less devel- 

 oped and more irregular in character. 



Spore coat. — Variable in thickness, 

 generally relatively thick on abortive and 

 considerably thinner, especially in the 

 median areas, on fertile spores. Pyramic 

 areas of fertile forms are thinner but the 

 more proximal portion immediately distal 

 to the arcuate ridges is thick ; the median 

 portion of the spore is membranous and 

 the extreme distal portion may again be 

 somewhat thicker. The most characteristic 

 feature of this genus is the fibrous char- 

 acter of the spore coat in the membra- 

 nous middle region ; thicker parts of the 

 coat also consist of thicker matting of the 

 interlocking, variable width, anastomos- 

 ing fibrils. A thinner nonfibrous endo- 

 sporal membrane may be present. The 

 fibrous spore coat is evidently equivalent 

 to the exospore. 



Affinites. — Cystosporites is a member 

 of the Lepidocarpaceae. It is intimately 

 related to the genera Lepidocarpon, Illi- 

 niocarpon, and probably others of this 

 family in which the correlation has not 

 been as definitely established (Schopf, 

 1941). Spores of Cystosporites, although 

 highly specialized with reference to semi- 



nal adaptation, appear to be generalized 

 so far as specific differences are con- 

 cerned. The ornamental patterns which 

 serve to distinguish spores of free-spor- 

 ing lycopsids have evidently undergone 

 extensive reduction if such characteristics 

 were ever present in the line of lepido- 

 carp ancestry. The genus Cystosporites 

 thus expresses a broader relationship 

 than that exemplified by other genera 

 in the Lepidocarpaceae, and, so far as is 

 known, is inclusively correlative with the 

 lepidocarp family. Future discoveries may 

 make it possible to restrict this group and 

 establish relationships in greater detail. 

 The spores found within the seeds of 

 lepidocarp species are receiving more de- 

 tailed study now (Reed, 1941 ; Darrah, 

 1941 ; Hoskins and Cross, 1941 ; Schopf, 

 1941) and further studies may show 

 other features of the spore coat that have 

 unsuspected systematic significance. 



Zerndt (1930, et seq.) has classified 

 some forms now placed in Cystosporites, 

 under Triletes. The distinction between 

 free-sporing and seed-bearing lycopsids 

 seems at least familial in its importance 

 (Schopf, 1941) and this distinction is 

 most in evidence when the megaspores 

 are compared. 



Remarks. — The fertile and abortive 

 megaspores of species of Cystosporites are 

 very heteromorphous. In several instances 

 they have been recovered in tetrad group- 

 ings from maceration residues of coal. 

 They nevertheless are generally separated 

 from one another so that a system of 

 treatment for the isolated tetrad members 

 both fertile and abortive seems essential 

 for scientific reporting. The characters of 

 the fertile spores are used to identify 

 species, and fertile specimens serve as 

 holotypes for the two species listed below. 

 Isolated abortive spores may be distin- 

 guished in classification as formae. The 

 procedure may serve as a practical means 

 of expressing relationships between these 

 heteromorphous spore types and still re- 

 tain for each of them a nominal distinc- 

 tion. There appear to be no inherent dis- 

 advantages in such a policy, as it affords 

 a means of more accurate recording of 

 actual material encountered ; only the ac- 

 crual of additional information can show 

 whether such a practice, in fact, is neces- 

 sary. If the formae later appear super- 

 fluous in some instances and worthy of 



