94 NEW YORK STATE MUSEUM 



Spathiocaris emersoni Clarke 

 Plate 31, figures 7 and 8 



Since this species was described in Palaeontology of New York, 

 volume 7, page 199, larger and more perfect specimens have been 

 observed by Mr Luther in the Portage (Naples) beds at Naples, 

 N. Y. The most remarkable feature of these specimens is their 

 much greater elongation than that shown by the earlier stages and 

 especially the strong bending downward or the lateral compression 

 of the sides instead of the vertical compression which all fossils 

 have normally suffered in these undisturbed beds. This lateral 

 compression which is uniform in all these larger specimens, would 

 seem to indicate either an original, highly convex form of the 

 conchiolinous valves or their connection with a body that shrank 

 after death bringing the two anterior wings or angles close together. 

 A cartilaginous substance would supply the required medium for 

 such a shrinking process (see p. 101). 



These specimens differ markedly from the strange valve figured 

 with S. emersoni on plate 35, figure 13, (Pal. N. Y., v. 7), 

 which latter possesses a much broadened flat posterior fold or 

 extension, and a very shallow anterior notch. If this unique speci- 

 men, which is in the State Museum, is not an entirely abnormal 

 individual of S. emersoni, it represents a widely different 

 form. Aside from the posterior lobe it is also quite distinct from 

 the large specimens of S. 'emersoni before us, both in out- 

 line, being relatively much broader, and in the shallow frontal notch 

 with sigmoidally curved margins. The separation of the median 

 lobe with diverging margins it has in common with Woodward's 

 genus Pholadocaris. We therefore venture to separate it from 

 S. emersoni as Pholadocaris lutheri sp. now 



Spathiocaris lata now 



Plate 31, figure 6 



Description. Valve semielliptic in outline; its length five-sixths 

 of its greatest width which is near the anterior margin; anterior 

 notch forming a very obtuse angle. Surface depressed convex, the 

 apex about one-quarter of length posteriorly of the anterior 

 margin ; posterior slope flat, lateral slope declining more steeply to 

 the antero-lateral angles. The surface sculpture consists of coarse 

 concentric, folds which carry a system of concentric lines so fine 

 that they are not visible to the naked eye. Behind the point of 



