GENUS TRILETES 



21 



spines, whereas megaspores of other cones 

 of the same species were practically devoid 

 of subsidiary spines. 



The few Illinois megaspores devoid of 

 subsidiary spines all possessed rather thin 

 (15 fx) distal spines up to 61^ in length 

 (pi. 2, fig. 7). These few spores seem to bear 

 a similarity to those originally decribed by 

 Zerndt (1934) as Lagenicula kidstoni (in- 

 cluded within Triletes subpilosus by Dijk- 

 stra, 1946). 



The megaspores of Triletes horridus 

 found in the Degonia Formation (pi. 2, 

 fig. 6), in older coals of the Caseyville 

 Group, and in the Tarter Coal of the 

 Tradewater Group (pi. 3, fig. 1) are typical 

 of T. horridus spores as previously de- 

 scribed in the literature. The megaspores 

 found in the "Makanda" Coals have gener- 

 ally shorter spines (50 to 87 ll) and a thin- 

 ner (7 to 11 f,i) spore coat (for example, pi. 

 2, figs. 9, 12). Their form and spine shape 

 and distribution are very similar, however, 

 to those illustrated for T. horridus by 

 Chaloner (1953b, fig. 2, 2a) . 



Megaspores of Triletes horridus also oc- 

 cur abundantly in the youngest coal of the 

 Mary Lee Group and in the youngest coal 

 of the Pratt Group in the Warrior Basin of 

 Alabama. Those of the latter coal are typi- 

 cal for the species; some of those in the 

 Mary Lee Group possess distal spines of two 

 sizes, expanded basally and pointed, but 

 their longest spines are only 20 fx in length. 

 In the length and distribution of spines and 

 in the expanded type of apical develop- 

 ment, these megaspores seem similar to that 

 originally illustrated by Ibrahim (1933, 

 pi. V, fig. 40) as Setosi-sporites subpilosus. 



Affinity. — Chaloner (1953b) described 

 these spores, in association with Lycospora- 

 type microspores, from cones of Lepidostro- 

 bus dubius. 



Previously Reported Occurrences. — Mega- 

 spores of Triletes horridus have been found 

 in three coals of the Michigan Basin by Ar- 

 nold (1950). They also have been reported 

 from the Westphalian A-D from the Neth- 

 erlands by Dijkstra (1952c), from east 

 Upper Silesia and Mahrisch-Ostrau by 

 Horst (1955), and from the Upper West- 



phalian B of the Ruhr Basin by Potonie 

 and Kremp (1955). T. horridus-type mega- 

 spores are found in cones occurring in the 

 Westphalian A-B from Scotland and Eng- 

 land (Chaloner, 1953b). 



Occurrence. — Megaspores of Triletes hor- 

 ridus are abundant in the Degonia Forma- 

 tion (maceration 200) of upper Chester age 

 and are present in varying degrees of abun- 

 dance in some Caseyville coals (macerations 

 795, 796, 798), in the "Makanda" Coals 



(macerations 905, 906, 907, 142) of the Ca- 

 seyville Group, and in the Tarter Coal 



(maceration 914) of the Tradewater Group. 



Triletes crassiaculeatus (Zerndt) Schopf, 

 Wilson, and Bentall, 1944 



Plate 3, figures 2, 3 



1937 Lagenicula crassiaculeata Zerndt (1937a), p. 

 12-13, fig. 9. 



1944 Triletes crassiaculeatus (Zerndt) Schopf, Wil- 

 son, and Bentall, p. 21-22. 



1946 Triletes crassiaculeatus (Zerndt) Dijkstra, p. 

 44-45. 



Description. — Megaspores large, typically 

 bottle-shaped (pi. 3, fig. 2) with large ex- 

 panded apex, generally laterally com- 

 pressed; maximum diameter, measured per- 

 pendicular to the spore axis, from 1370 to 

 1795 ix\ total length reaching 2300 p. Tri- 

 lete structures well developed; apical prom- 

 inence, measured from base of lip and not 

 from level of arcuate ridge, from 280 to 

 565 fx in height and 460 to 670 fx in width. 

 Lips and contact areas generally unorna- 

 mented, rarely bearing scattered, tiny 

 spines. 



Distal surface bearing closely spaced 

 spines of two sizes. Large distal spines ex- 

 tending 125 to 290 f x in maximum length 

 from a fluted base 20 to 75 ^ wide (pi. 3, 

 fig. 3), terminating in a sharp point or in a 

 ball- to cup-shaped expansion surmounted 

 on the slender neck. As many as three of 

 four large distal spines may be forked at 

 their tips. Large distal spines decrease in 

 length by about one-half and are more 

 closely spaced toward margins of contact 

 areas. Subsidiary acuminate distal spines, 

 up to 36^ in length and 10^ in width, are 

 scattered between the large distal spines. 



