Benson.—Mazocctrpon or the Structural Sigillariostrobus. 579 
sporange which is sharply defined. In fact we may note that with the 
exception of this single layer the rest of the persistent sterile tissue is not 
differentiated into tapetal tissue and parenchyma, but largely partakes of the 
character of the former. 1 There is as yet no evidence of the existence of 
a sporangial lamella. 
Owing to these distinctive characters, which mark it as a less specialized 
type, and the great antiquity of these specimens it is desirable to give them 
specific rank, and the name M'azocar pon Petty curense is proposed until they 
are more fully known. 
Mazocarpon Shorense. The great bulk of the specimens of Mazocar pon 
described in this paper have been secured from coal balls from many 
localities in the Yorkshire Lower Coal Measure beds. One cone, the 
microsporange, and the megasporange from which Text-fig. 2 is taken, were 
obtained from Shore balls. Those which agree with these specimens 
I propose to refer to as Mazocarpon Shorense. The diagnosis will be 
found as a summary of the characters given in the next section (Section IX). 
Mazocarpon Cashii. Specimens of this species occur in one slide, 
M. Cn. 472 A, which must be regarded as the type slide. The specimen is 
given specific rank because of two characters by which it may be dis¬ 
tinguished from M . Shorense. The leaf-traces as seen in a transverse 
section of the cone-axis are surrounded by a sheath as they pass out through 
the lacunar middle cortex. The transfusion tissue of the base of sporange 
(see Fig. 15) is more highly differentiated than that observed in M. 
Shorense. 
Other specimens show slight deviations from M. Shorense. Thus the 
sporange from Dulesgate (Fig. 6) has a wider lamina than would be seen in 
a tangential section through sporange and keel in M. Shorense , but there 
are not sufficient data for distinguishing a new species. The sporange of 
M. Shorense differs so much with its age and place on the cone that a con¬ 
siderable range of variation in detached sporangia must be expected. It is, 
therefore, inadvisable to multiply species, more especially as it is the aim of 
the Palaeobotanist to avoid as far as possible leaving a fossil long in a mere 
form genus such as Mazocarpon . If we can show that Mazocarpon is 
Sigillariostrobus , the probability is very high that some at least of the 
specimens of M. Shorense are the fructifications of Sigillaria mamillaris 
with which many of them occur. 
Section IX. Summary of Part /. 
Mazocarpon is a provisional term used for a form genus of the structural 
remains of a sporangial apparatus of a Lycopsid type. 
The cone bore, in a close spiral, cone-scales of the Lepidostrobus 
1 See Benson, loc. cit., p. 144, Fig. 25, a and 0', where ci f is magnified thirty-nine times and a only 
thirty times. 
