NEW YORK STATE MUSEUM 



SPATHIOCARIS AND THE DISCINOCARINA 



In view of the description of two new species of Spathiocaris 

 and the observation of some new features, we venture to touch the 

 much discussed problem of the nature of this interesting genus 

 and of the suborder Discinocarina of the crustaceans in general. 



Doctor Clarke has in 1902 1 in a chapter on " The organic bodies 

 called Discinocaris, Spathiocaris, Cardiocaris, Pholadocaris, etc." 

 furnished a full history of the discussion that has been waged 

 about these problematic crustaceans. It will suffice here to mention 

 that the group of fossils of which Spathiocaris is one of the most 

 characteristic representatives are " all thin, chitinous, tenuous, oval, 

 or cordate shields, bearing a deep triangular slit at one end extending 

 back to the apex of the shell, about which the growth-lines are con- 

 centric " ; further, that they have been considered by some authori- 

 ties (H. Woodward, Clarke) as crustaceans, by others (as Roemer, 

 de Verneuil, Kayser and Dames) as aptychi of goniatites. The 

 discussion which was carried on in the early nineties by these 

 authors has remained undecided for lack of sufficient evidence 

 either one way or the other. Since that time the question has been 

 but incidentally touched, first by Holzapfel 2 who discusses the 

 probable nature of Spathiocaris after having had access to the 

 material from the Domanik shale in Russia that was originally 

 described by Kayser and de Verneuil as an aptychus. Holzapfel, 

 proceeding on the assumption that the aptychus was an operculum 

 of some goniatite ,or ammonite, claims that the famous cases of 

 valves of Cardiocaris and Spathiocaris found within the living 

 chambers of goniatites (Manticoceras intumescens) 

 are nonconclusive for the operculum or aptychus-nature of these 

 organisms, since the specimens do not fit the apertures of these 

 living chambers at all and may be there by accident. While it may 

 be true that these bodies could not have been used as opercula, 

 it is still known that aptychi had probably a different function 

 than that of opercula and they could have served another 

 function. There are two views at least differing from that con- 

 cerning the aptychi as opercula (see below, p. 101). Holzapfel sees 

 further proof of his view in the fact that the goniatites and aptychi 



. x N. Y. State Mus. Bui. 52 : Rep't State Pal. for 1901, p. 610. 1902. 



2 E. Holzapfel. Die Cephalopoden des Domanik im siidlichen Timan 

 Mem. du Comite Geo!'., v. 12, no. 3, p. 48. 1899. 



