LASIOGRAPTUS. 329 



This form was originally described from a single specimen from the Llandeilo 

 Shales of the neighbourhood of Llandrindod (PI. XXXIV, fig. 3 a). We figure 

 also two other specimens which may belong to this species. The one (from 

 Scotland) (PI. XXXIV, fig. 3 b) has rather more distant thecas, the other (from 

 Cwm Brith Bank, Llandrindod Wells) (PL XXXIV, fig. 3 c) is wider (2-5— 3 

 mm.) and has more closely-set thecae ; this may possibly show the obverse aspect. 

 In the last example the spines are more conspicuous than in the type specimen. 



Affinities. — Th. retusus differs from the other Thysanograpti to which it is 

 allied in being a longer form, in having a distinct zig-zag septal groove, and in the 

 absence of a lacinia. 



Horizon and Localities. — Upper Arenig, Llandeilo. 



Radnorshire : N. of Llandrindod Wells ; N. of Cwm Brith Bank, nr. Llandrindod 

 Wells. S. Scotland: Hartfell Spa ?. 



Associates, etc. — Th. retusus occurs in the Llandeilo Rocks of Llandrindod 

 associated with Gryptog. tricornis, var. Schaferi, and at a somewhat lower horizon 

 associated with Didymog. Murchisoni, var. geminus. 



Collections. — Lapworth and Miss C. Chamberlain, Birmingham. 



Sub-genus Nymphograptus, Lapworth, MS. 



As only one species of this sub-genus is at present known, its characters may 

 in the main be regarded as typical for the sub-genus. 



Lasiograptus (Nymphograptus) velatus, sp. nov. Plate XXXIV, figs. 4« and b. 



Polypary relatively large, at least 4 cm. in length, widening gradually from 

 1 mm. to a maximum breadth of 4 mm. Thecaa seven to six in 10 mm., of 

 the general type of those of Hallog. mucronatus. Septal strands very 

 strongly developed, extraneous processes filiform, united to form a broad 

 and composite lacinia completely surrounding the polypary. Test con- 

 tinuous, fairly thin. 

 Description.- — Of this fairy-like species only three examples are as yet known — 

 one shown in the bi-profile view and two (on the same slab) in the scalariform 

 view. 



The most striking feature of this form is presented by its remarkably 

 complicated lacinia. This is formed of a symmetrical arrangement of fine strands 

 and delicate cross-filaments. So far as can be gathered from the appearances 

 presented, this lacinia is composed of two main elements, namely, a first set of 



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