3§4 



COLLEGE ZOOLOGY 



Order 10. Eurypterida (Fig. 3 28). — The Eurypterida 

 lived in both salt water and fresh water during the Silurian and 

 Devonian periods (Table XVII), and are known to us only as 

 fossils. They appear to represent a condition intermediate be- 

 tween Limulus and the Scorpionidea. 



Fig. 328. Fig. 330. Fig. 331. 



Fig. 328. — Order Eurypterida. Eurypterus fischeri, dorsal surface. 

 a, ocellus; b, lateral eye; 2—6, appendages of prosoma; 7-12, segments of 

 mesosoma ; 13-18, segments of metasoma; iq, tail spine. (From the Cam- 

 bridge Natural History, after Holm.) 



Fig. 329. — Pycnogonida. Ammothea pyenogonoides. (From Sedgwick's 

 Zoology, after regne animal.) 



Fig. 330. — Tardigrada. Macrobiotus schultzei. Md, stomach; 0, mouth; 

 Ov, ovary; Spd, salivary glands; T, malpighian tubules; Vm, pharynx; Vs, 

 accessory gland. (From Sedgwick's Zoology, after Greeff.) 



Fig. 331. — Pentastomida. Pentastemum ianioides. A, anus; D, intes- 

 tine; Hf, hooks; O, mouth. (From Sedgwick's Zoology.) 



