696 



SILURIAN NONDESCRIPTS. 



also named for the first time in the Xllth edition of the Syst. Nat. vol. iii. p. 174. No. 7. as G. 



scalaris. 



"In the last-mentioned work the genus Graptolithus is reproduced; but several fossil bodies, and 

 even some inorganic markings and veins in rocks being united as species under the same generic 

 denomination, the real typical form was nearly lost by this intermixture. This confusion was 

 carried still further in the XHIth edition by Gmelin, where even all the true graptolites were 

 omitted. Wahlenberg restored the genus, all the forms given by him being those fossil bodies 

 which belong to the typical species of the transition formations, but he only gave a superficial ac- 

 count of the subject. Schlotheim referred them to the genus Orthoceratites, and several other 

 authors who followed added no original matter. Professor Nilsson of Lund undertook a mono- 

 graph of the species of graptolites found in Sweden. But he was prevented by circumstances, into 

 which I need not here enter, from continuing his investigations on fossil remains, and some brief 

 remarks only were published by him upon this interesting genus in the proceedings of the Physio- 

 graphical Society of Lund. In that notice he proposed a new name for the genus, altering it to 

 that of Priodon, a name not only objectionable as being unnecessary, but as having been already 

 employed by Cuvier for a genus of Acanthopterygian fishes of the family Teuthidce. 



"Since that time no attempt has been made to write a monograph. Professor Bronn of Heidel- 

 berg in his Lethsea Geognostica, again, however, changed the name of the genus to Lomatoceras 5 

 a name already given to an insect 1 ." 



NONDESCRIPTS. 



Spongarium Edwardsii. PI. 26. f. 10. 



This singular fossil has not been described by any English naturalist. I had not, indeed, met 

 with any one who could throw light upon its probable origin, until, in 1836, I showed it to 

 Dr. Milne Edwards, who was then on a visit to this country; on which occasion he took a 

 sketch of the specimen, and has since favoured me with the following description, extracted 

 from his note-book. 



" The nature of the orbicular fossil is very problematic. At first sight it might be taken 

 for a cartilage of Velella, or for some marine plant bearing an analogy to Zonaria pavonia 

 (D'Agarth), or still more probably for a Cyclolite of Lamarck, all the superior portion of which 

 maybe supposed to have disappeared in the stony matrix, and the inferior surface of which only 

 has remained visible. In fact, many small ridges or obtuse cristse may be observed on it, 

 which, radiating from a common centre, are crossed by salient circular lines, similar rather to 

 membranaceous folds than ribs (cotes). On examining, however, more closely these objects, 

 we perceive that all these analogies are erroneous ; for the radiating ribs of this fossil are not 

 straight lines, between which, in proportion as they widen out, other and similar lamellse are 

 developed (as in the Cyclolites, Sec.) \ but they ramify irregularly, in extending from the central 

 point. 



1 In consequence of the views of Dr. Beck, and sanctioned by the advice, of Mr. Lonsdale, I have inserted 

 the Graptolites in the list of Polyparia, between the genera Limaria and Cladocora (see p. 711). 



A beautifully illustrated book on the Swedish fossils has recently been published by Hisinger, in which the 

 generic name of Nilsson " Prionotus" has been continued.. The highly useful work of BrOnn was, I regret to 

 say, unknown to me till too late to be referred to in the description of many of the other fossils. — R.I.M. 



