196 DEVONIAN FAUNA. 



2. SUB-ORDER TREPOSTOMATA, Wrick, 1882. 

 I. Family BATOSTOHELLID^E, Ulrich, 1890. 



1. Genus LEIOCLEMA, Ulrich, 1882. 

 1. LEIOCLEMA? DISTANS, Wkidborne. Plate XXITI, figs. 16, 16 a. 



1896. KHABDOMESON ? DISTANS, Whidborne. Proceed. Geol. Assoc., vol. xiv, 



p. 376. 



Description. Zoarium small, ramose, cylindrical. Zooecia small, elongate, 

 oval, separated from each other by interspaces considerably greater than their 

 diameters. Interspaces apparently flat, and occupied by numerous thin-walled 

 mesopores (?) Cell-mouths possibly covered with convex opercula (?). 



Size. A specimen measures 11 mm. long, and 1 mm. in the width of the 

 branch. 



Localities. In the Woodwardian Museum are two slabs containing two 

 specimens from Top Orchard, and in Mr. Hamling's Collection two slabs with two 

 or three specimens from rocks to the north-west of the " Laticosta Cave," Croyde. 



Remarks. This species is similar in habit to R. gracile, but is clearly dis- 

 tinguished from it by its smaller and much more distant cell-mouths, and by the 

 existence of numerous small mesopores round the larger cells, evidence of which is 

 seen in the Woodwardian specimens, which are in the form of moulds, and which 

 also show slight ridges dividing the cell-areas. 



In the Croyde specimens, on the other hand, which retain the surface, though 

 probably worn, the cell-mouths form small convex projections, which may perhaps 

 mean that they were covered by opercula. In parts of the latter specimens which 

 are worn to form rough natural sections the cells appear to be short conical tubes, 

 rapidly curved, and enlarged in the mature part or vestibule. 



In this species (assuming that sections like that shown on PI. XXIII, fig. 15, 

 do not belong to it) we do not appear to have any approach to Rhabdomeson, 

 while it presents a general likeness to Batostomella ; its external resemblance to 

 Leioclema gracillimum, Ulrich, 1 is so strong, that it seems advisable to refer it 

 provisionally to that genus. 



The genus Hyphasmopora, Etheridge, 2 certainly appears to have much in 

 common with it. Its cells are in vertical lines, separated by a cancellated network 



1 1890, Ulrich, ' Geol. Surv. Illinois,' vol. viii, p. 429, pi. Ixxv, Bgs. 66 b. 



1875, J. Etheridge, jun., ' Ann. Mag. Nat. Hist.,' ser. 4, vol. xv, p. 43, pi. xiv, figs. Bl 4. 



