BUB-GLASS I 



MATA 



is tin! cleft-shape* 1 nmutli, whi.-h is honored laterally l-y th- basal segment* 

 fifth pair of legs, and poetei -im-Iy l>y the large oval metastoma. 



The first pair of appendages were regarded by Woodward and Schmidt a* lililon 

 tactile. Laurie and Holm, however, h;ivr found rviden. tint : a.-, and thus 



more nearly in accord with homologous strin'tun-s in other nicinl'ers of tin- f.uuilv. The tlm-.- 

 succeeding appendages are six- or seven -join ted, mnl eovend with In 

 of legs is eight-jointed, and longer than those in front of it. The posterior pair Ua p 

 swimming organ ; its great sul>- 

 quadrate basal joints enclose the 

 metastoma, and together with this, 

 cover nearly one-half of the ventral 

 side of the cephalothorax. 



The six anterior abdominal seg- 

 ments together occupy about one- 

 fourth of the body -length. They 

 are short and broad, and nearly 

 uniform in shape ; but the second 

 segment has lost its hard skeleton 

 on the ventral surface, and the first 

 covers the greater part of the genital 

 operculum. This first segment joins the posterior 

 margin of the cephalothorax and consists of two lateral 



FIG. 1418. 



Eurypterus Fischeri, Eichw. Silurian; Rootzikiill, Island of 

 Oesel. Ventral aspect. II. VI., Appendages with the joints 

 numbered. I'. V'., Lamellar appendages of tV umli-r ndfl "f 

 abdomen, divided by median suture. I'., First of these, or 

 "operculum," composed of two portions (b, I'). For abdominal 

 segments after 7 see next figure. Vi (after F. Schmidt). 



Fio. 1419. 



Fischeri, Eichw. Silurian; 

 bland of OaseL F-maln individual, 1/3 



(from Holm). 



The first six segments are moderately overlapping 



Tin- following six 



on the 



portions and a median process. 



ventral side, and divided by a median suture or cleft into two parts. 



abdominal segments are ring-like, tapering posteriorly, and the boay is terminated by a long 



slender telson. 



About twenty-five species of Euryptcrus are known, the largest being about 40 cm. long. 

 They are found for the most part in argillaceous or sandy deposits in transition strata 1 

 the Silurian and Devonian of England, Gottland, Oesel, Podolia, and in tin- Watcrlinu- Group 

 of New York. They are rare in the Devonian, but occur again more frequently in the Coal 

 Measures of Scotland, Silesia, Bohemia, Saarbriickeu, and Pennsylvania. The last survivor 



