hitrodudion to A7iimal Morphology. 205 



and eight of water. Trachelobdella has no ocelli, and a 

 round retractile neck (found on Gobius Capito). Bdella 

 has a deep grove on the under side of the fore lip. Podo- 

 bdella is elliptic, closely ringed, without eyes or teeth, and 

 with a stalked sucker. Pinacobdella has an elongate body, 

 with seventeen dorsal scutella and no eyes. Typhlobdella 

 sub-lanceolate, with 81-93 rings, three jaws, no eyes; it in- 

 habits the subterranean waters of the Baradla cave at Aggtelek, 

 Hungary. Its orifices are as in Hirudo. 



Class 8. Onychophora [Grtihe). — One genus 

 (Peripatus) with an elongated, cylindrical body of 

 several metameres, head lobes and mouth segments 

 united, and with two frontal feelers and two eyes. 

 The mouth is very shortly protrusible, with two 

 parallel, hook-like teeth. The pharynx is short, 

 divided into a wide anterior and a narrower posterior 

 part. The stomach forms a simple tube, ending in a 

 short narrow intestine. There is a soft epidermis, a 

 connective dermis, three muscular layers as in leeches, 

 and no surface bristles ; but each of the down-directed 

 feet bears a single, double, or multiple chitinous claw. 

 The vascular system consists of a single dorsal stem. 

 Two lateral canals exist imbedded in the muscular 

 laminae, which may also be vessel stems, but they 

 have a glandular lining [Gi'iibc). No other excretory 

 organs are described. The nerve system consists of a 

 pair of closely united, large ganglia above the 

 pharynx, which send branches on each side of the tube 

 to unite below. Two diverging, ventro-lateral cords 

 arise here, which unite at the end, and the two cords 

 (which are coated with nerv^e cells) are joined by many 

 fine commissural threads. There are six single 

 branches from the cord in each metamere, but there 

 are no special ganglionic differentiations in its course. 



