Ruedemaknj— Sessile Conularia. 



707 



be remarked that the largest specimen in the writer's collection (length 14.3 

 cm.) is preserved to a breadth of 4 mm. and ends in a deep impression which 

 could be caused by a cup not Larger than the largest w ell preserved one which 

 has been found. Further, it will be noticed that some of the attached shells 

 (PI. IV, fig. 40; PL II, figs. 1, 7) have already readied a size which renders 

 it improbable that the enclosed animals should still have changed their 

 1 1 1 < »de of life. 



After having presented the general features of the occurrence of a sessile 

 Conularia, the writer intends now to describe the most novel part of the 

 fossil, i. e., the basal appendage. 



Though an attempt to isolate and decolor some of the appendages failed, 

 partly on account of an obscure cleavage in the rock and partly on account of 

 the consistency of the residuum after the treatment with acetic and hydro- 

 fluoric acids, the author succeeded at least in developing, by the application 

 of the same agents, several of the stout chitinous appendages on the slabs 

 (cf. PI. Ill, figs. 5 and 16). The defects in the preparation of the material are 

 atoned for by the well-preserved state of the material itself, for several of the 

 bases are preserved in neat natural sections (cf. PI. Ill, tigs. 2 and 3), a com- 

 parative study of which, as well as of the varying aspects of the other bases 

 allows a fair insight into the structure of this interesting organ. In order 

 to enable the reader to form for himself a picture by a comparison of 

 the different states of preservation, the writer has given as many sketches as 

 possible. 



As already stated in the first article, most bases appear at first sight as 

 stout subcircular to suboval chitinous rings* (cf. PI. Ill, fig. 1, which is the 

 base of the specimen reproduced on PI. II, fig. 1). The original form was 

 probably circular, as the elongated forms (cf. PI. Ill, fig. 20) are generally 

 found near the edge of the supporting fossil (cf. PI. I, figs. 1 and 2), 

 where they were more liable to become laterally compressed than those on the 

 inner part of the fossil. 



* These rings; were observed by A. G Nathorst as early as 1882 (cf. A. G. Nathorst, " Om fiirekomsten af Uphenothallus 

 cfr. anguxtifoliuf. Hall, i silurisk skiffer i Vesterg'itland" in Geologiska Fiireningeris i Stockholm Fiirhandliugar, Vol. VI, p 315, 

 PI. 15). The same author has published in the April (18!Ki) number of the same journal (Vol. XVIII, No. 1). under the caption, 

 '• Sphmothallus eu Conularia." a review of the study of this interesting fossil in Sweden, from which it appears that he, in 

 describing, in the first cited paper, a specimen of Spkenothallus, Hall, from the Silurian shale in the neighborhood of Vamb in 

 Westgotbland. accepted Hall's interpretation of the fossil as an alga. Some years later, however, another specimen was sent to 

 him by Dr. N. O. Hoist, the state of preservation of which was such as to convince Nathorst at once of the impossibility of 

 referring the fossil to the vegetable kingdom. He [minted out this fact to Hoist, who afterwards sent the same specimen to J. 

 Chr. Moberg for identification. The latter reached the same conclusion, as appears from an extract of a letter of his to 

 Nathorst: ' It seems to remind me somewhat of a Con ularia, and above all it surely was not an al^'a." Nathorst himself now 

 accepts the identification of Sphenothallns with Conularia. Hall's type is not so well preserved as to have been able to suggest 

 a comparison with Conularia. 



