RETICULATI-SPORITES 



35 



tion. This form, R. facetus (Ibrahim), 

 was originally designated as the genotype 

 of Reticulata-s pontes with five species 

 assigned to it. Essentially the only char- 

 acter shared by these five was their lack 

 of a visible haptotypic marking. Most 

 diverse types of reticulation characterized 

 their surfaces. R. facetus, however, shows 

 a type of reticulation which is very simi- 

 lar to that of R. reticulatus (genotype of 

 Reticulati-sporites) and others in this 

 genus. Other characters are also in sub- 

 stantial agreement and it is believed that 

 the lack of a trilete marking in this case 

 is insufficient basis for generic separation. 

 Other species of Reticulati-sporites show 

 a very weak trilete marking. Consequent- 

 ly Reticulata-sporites Ibrahim (1933, p. 

 38) may be dispensed with and regarded 

 as a later synonym for Reticulati-sporites 

 Ibrahim (1933, p. 33). 



Knox (1939) has suggested that alete 

 spores with somewhat spiral reticulation 

 such as shown by R. facetus (cf. fig. 49) 

 resemble spores of Riccia but this com- 

 parison does not seem particularly close. 

 Neither does the comparison of the R. 

 corporeous type with Fossombronia spores 

 seem appropriate because the fossil forms 

 evidently have a perisporal membrane en- 

 closing them instead of mere "large alve- 

 olae with high lamellae." ISTevertheless it 

 must be admitted that in general spores of 

 Reticulati-sporites bear more resemblance 

 to some of the spores of the Hepaticae il- 

 lustrated by Knox than any of the other 

 Paleozoic groups. The apparent absence 

 of haptotypic markings on several of the 

 modern forms is a striking feature which 

 should be more thoroughly investigated, 

 although it need not occasion great sur- 

 prise to find so advanced a character in 

 a group whose discrete phylogeny goes 

 back at least to the Carboniferous. 



It may be suggested that spores of 

 Reticulati-sporites underwent more mod- 

 ification within the sporangium subsequent 

 to the breakup of the original tetrad than 

 is usual for cryptogamic spores. The 

 highly developed reticulation pattern prob- 

 ably was laid down relatively late in sporo- 

 genesis by a tapetal plasmodium, some- 

 times without respect for the proximo- 

 distal relationships established in original 

 tetrad groupings. Such a sequence occurs 

 in formation of many kinds of angi- 

 ospermic pollen. Spores of Reticulati- 



sporites apparently lack the further spe- 

 cialization of germinal pores, neverthe- 

 less lack of good development of a trilete 

 commissure in some of the forms might 

 possibly signify that the plants repre- 

 sented here had passed beyond the typi- 

 cal cryptogamic stage of evolution. Re- 

 ticulati-sporites appears to be a relatively 

 homogeneous group of natural relation- 

 ship. The coarse reticulation is highly 

 characteristic and for the most part quite 

 unmistakable. Nevertheless these forms 

 are rather anomalous in their morphology 

 and offer difficulties in interpretation. 

 Those suggested are regarded as tenta- 

 tive only. 



The genus is best known from the Aegir 

 coal bed at the top of the Westphalian B, 

 which is approximately equivalent in age 

 to middle Des Moines and upper Potts- 

 ville-lower Allegheny beds. 



1. Reticulati-sporites corporeus Loose, 1934, 

 Inst. Palaobot. Arb., vol. 4, no. 3, p. 155, 

 pl. 7, fig. 7. 



2. Reticulati-sporites facetus (Ibrahim) 

 S. W. and B., comb. nov. 



Reticulata-sporites facetus Ibrahim, 

 1933, Sporenformen des Aegirhorizonts, p. 

 38, pl. 5, fig. 36. 



3. Reticulati-sporites mediareticulatus Ib- 

 rahim, 1933, idem, p. 34, pl. 7, fig. 62. 



4. Reticulati-sporites ornatus (Ibrahim) 

 Ibrahim, 1933, idem, p. 35, pl. 1, fig. 7. 



Sporonites ornatus Ibrahim, 1932, Neues 

 Jahrb., Beilage-Band 67, Abt. B, p. 447, pl. 

 14, fig. 7. 



5. Reticulati-sporites polygonalis (Ibra- 

 him) Loose, 1934, Inst. Palaobot. Arb., vol. 

 4, no. 3, p. 155, pl. 7, fig. 16. 



Sporonites polygonalis Ibrahim, 1932, 

 Neues Jahrb., Beilage-Band 67, Abt. B, p. 

 447, pl. 14, fig. 8. 



Laevigati-sporites polygonalis (Ibra- 

 him) Ibrahim, 1933, Sporenformen des 

 Aegirhorizonts, p. 19, pl. 1, fig. 8. 



6. Reticulati-sporites reticulatus (Ibra- 

 him) Ibrahim, 1933, idem, pp. 33-34, pl. 1, 

 fig. 3. 



Sporonites reticulatus Ibrahim, 1932, 

 Neues Jahrb., Beilage-Band 67, Abt. B, 

 p. 447, pl. 14, fig. 3. 



Reticulati-sporites reticulatus (Ibrahim) 

 Ibrahim, Loose, 1934, Inst. Palaobot. Arb., 

 vol. 4, no. 3, p. 156. 

 Note. — Type species of Reticulati-sporites. 



7. Reticulati-sporites (?) reticuliformis 

 Ibrahim, 1933, Sporenformen des Aegirhori- 

 zonts, p. 34, pl. 7, fig. 62). 



Note. — Trilete rays are unusually long and 

 well developed in this species. 



