Vol. 68.] LOWEE CARBONIFEEOUS GASTEEOPODA. 303 



down the middle and covered by distinct, deeply bent, more or less 

 horseshoe-shaped, raised threads, some of which are almost angular 

 at the extremity of the bend. Base flat. Aperture obliquely 

 oblong. 



Genotype. — Trechmannia trocMformis^ sp. nov. 



Eemarks and resemblances. — So far I have only met with 

 one species belonging to this genus that has the distinctive charac- 

 teristics well preserved. But I have seen several specimens that 

 may belong to another species which is larger and possesses more 

 convex whorls ; the band on these, however, is not in sufficiently 

 good condition to exhibit its structure clearly. 



Only one example of the genotype is known to me, and on it the 

 form of the band is distinctly seen. The sharply bent lunules are 

 suggestive of the existence of a deep slit in the outer lip ; they 

 cannot be the remains of broken chambers, such as have been 

 suggested for Euomjjhalopterus, as each curve has a finished and 

 unbroken appearance. The band greatly resembles that of Mur- 

 chisonia dejlexa Lindstr.^; but in that species only the lower margin 

 is produced, and the upper remains normal, leaving an opening. In 

 the present instance the lower margin is not only similarly 

 produced upwards, but tbe upper margin also is produced, though 

 not to such an extent, for the apex of the keel is above the centre 

 of the band. It is not clear whether the margins actually united ; 

 but, if they did not do so, the opening left was evidently not so 

 wide as that of M. deflexa^ and was probably not more than a 

 hair's breadth. The lunules also differ, those of M. dejlexa being 

 less sharply bent. In general form this subgenus greatly resembles 

 species referred to Ptychomphalina and il/oitrZonm, but the character 

 of the band distinguishes it from those genera. It also probably 

 differs from the former in having an open umbilicus ; but, as the 

 only individual that I have seen has a portion of the matrix 

 adhering to the base, and the opening is merely indicated by 

 the shell-structure, this is not absolutely certain. 



It is distinguisbed from Euomplialopterus not only by the 

 character of the lunules, but also by the keel being less prominent 

 and being situated higher on the whorl ; from Tropidostropha by its 

 much smaller size, flattened base, aperture receding below, and 

 deeper lunules on the band. 



Teechmannia teochifoemis, sp. nov. (PI. XXX, figs. 5 a-5 d.) 



Diagnosis. — As only one species is known at present, it is 

 impossible to add anything more distinctive than has already been 

 stated in the description of the subgenus. 



Remarks and resemblances. — This species greatly resembles 

 Pleurotomaria conica Phill., as figured in ' Illustr. Geol. Yorks.* 

 vol. ii (1836) pi. XV, fig. 22. The holotype of Phillips has not 

 been recognized, although among seven specimens on tablet G 148 in 



1 K. Svensk. Vetensk.-Akad. Handl. n. s. vol. xix (1884) No. 6, p. 134 & pi. xx, 

 figs. 1-6. 



