ON Tin; losjiiL rj[YF.LoroDA of tub paleozoic nocKS. 



93 



parato 

 ivexity 



fouml 



vmallev 



3 with 



. more 



ol. viii. 

 icalar, 

 I. c. 



* Quart. Jour. Geol. Soc' vol. xix. IRGo, p. 88, f. 1 (woodcut) gives a cir- 

 cular form ; but at p. I'U, f. I- (woodcut) gives an oval outline. 



In 18GG (^ Quart. Jonr. Gcol. Soc* vol. xxii. p. 504, pi. 25, f. G) Dr. 

 ]I. Woodward gave a eareful figure of this species from a good spocimen 

 (niea.suriiig 12i mm. in length ii'<.d 10 mm. iu width '), giving it its true 

 oval outline, nither hhuit at the cads, the rostral piece making a distinct 

 curve of its own at the front (^loHat). A distorted specimen is figured 

 in the 'Proc. Uelfiist Ts'at. Field Club,' 1877, Appendix, pi. 7, f. 24a, by 

 Messrs. Lapwortli it Swanston, from Tievcsliilly, near Portaferry, Co. 

 Down, Ireland. This is from either the top of the Middle Silurian or the 

 base of the Upper Sihirian ((7;. n't. p. 122). II. Woodward's figure is 

 reproduced in illustration here, fig. 24i ; and again by Mr. J. Dairon, 

 ♦Trans. Geol. Soc. Ghispow,' 1883, pi. 7, f. 2!t, for a Motfat specimen. 



Some specimens in the Museum of the Geological Survey are oval. 

 One (D;f*.), almost perfect, is a pyritous film, with the rostral piece in 

 place, and with obscure coneontrio lines; from the Llandcilo formation; 

 locality unknown. Specimen 1),^ is a black film; the shield has been 

 oval, but one half is modified by pressure. Upper Llandcilo ; Duif-Kennel, 

 Dumfries. 



In the ^luseum at Jermyn Street there is also an imperfect Peltocaris 

 (D ^"^g, from Motfat), of relatively largo size, length ?, width 24 mm., very 

 delicately and regularly concentric in its linear ornament; and it seems 

 to show what Mr. Salter intimated at p. 88, ' Quart. Jour. Geol. Soc' vol. xix. 

 — namely, that the umbonos, or angles at the front end of the median 

 sutures, may come away by the weakness of a small curved sntural lino 

 bounding them and concentric with the stria>. See also Mr. Salter's 

 drawing of the notch in 'Quart. Jour. Geol. Soc' vol. viii. pi. 21, f. 10. 



In the British I^Iuseum, a specimen (from the Grioston beds, Gala 

 Group, Rotten Gair, Inverleithen), slightly modified by pressure, was 

 probably almost oval in outline, 15 by 14 mm. Another, also broadly 

 oval when perfect, length about 10 mm., width IG mm., has somewhat 

 sinuous sides to the notch, that is, it widens in the middle and then con- 

 tracts, forming a small notch at its apex. Something like this, but not 

 quite the same, is seen in the figures of the natni-al size and enlarged at 

 p. 88, 'Quart. Jour. Geol. Soc' vol. xix.; it more closely resembles 

 fig. 10, pi. 21, 'Quart. Jour. Geol. Sue' vol. viii. 



2. PcUoraris anat'nm, Salter, 1873. 



In the ' Catal. Paliooz. Fossils Cambridge,' 1873, at p. 03, Mr. Salter 

 mentions this species, but it is not figured. The diagram annexed to it, 

 and given in illustration of the generic type, is P. aptijchoulen. That a 

 Pcltocan's was intended here is evident from the words, ' its semi-oval 

 rostrum is seldom found ; ' but the specimen (from Rebecca Hill) labelled 

 with this name in the Cambridge Museum is an Apti/chopsis (with angular 

 notch). Mr. Salter's intended species cannot therefore be recognised at 

 present. 



In this Museum there is an oval Phyllopod shield, with a semi-oval 

 notch, but it has been somewhat narrowed by lateral pressure, and the 

 notch may have been modified by the same cause. The suture, however, 

 cannot be made out : if it be absent, tlie specimen belongs to another 



' The statement that tlio tiguvc is magnified throe times seems to be a mistake in 

 the explanation of tlui plate. 



