vm, D. 4 Wharton: Some Philippine Thalassemx 247 



runs from behind the mouth to the anus. At its anterior end 

 it divides into 2 branches which run around the oesophagus and 

 enter the proboscis. The cord bears no gangha, but it gives off 

 numerous small branches which supply the body walls. 



Thalassema semoni Fischer. 



Thalassema semoni Fischer, Zool. Forschungsr. in Australien, etc, 

 Semon (1896), 5, pt. 3, 338; Shipley, Willey's Zool. Results (1899), 

 pt. 3, 351; Fauna and Geography of the Maldive and Laccadive 

 Archipelagoes Echiuroidea (1902), 1, pt. 2, 129. 



Two specimens of Thalassema semoni Fischer were collected on 

 Buquete Island in holes in a sandstone rock along with many 

 specimens of T. griffini (see page 249). 



The body when extended was about 7 cm. long. The proboscis 

 was about three-fourths that length, and was broad, flat, and 

 slightly truncated. The proboscis broke from the body very 

 easily, and did not leave a visible scar. Both of the specimens 

 were perfect when they were found, but their probosces were 

 broken off before they could be brought to the laboratory. The 

 bodies of the preserved specimens are 4 cm. in length and 15 mm. 

 in diameter; the probosces are greatly contracted. The body 

 wall is rather tough, and is covered uniformly with papillae. 

 The two ventral hooks are present, but are very small and in- 

 conspicuous. The longitudinal muscle layer is continuous, show- 

 ing no division into bundles. 



Both the body and the proboscis were olive green when the 

 animals were alive. In formalin they turned to dirty gray. 



There are 2 pairs of nephridial sacs each bearing spirally 

 twisted nephridia. The sacs are very long in proportion to the 

 length of the body, the posterior pair in one specimen being 

 longer than the body when straightened out. They are con- 

 stricted at intervals, and contain partly developed eggs. The 

 anterior pair opens in front of, and the second pair behind, the 

 ventral hooks. 



The anal trees are slender brown tubes about two-thirds as 

 long as the body. They are covered with very small ciliated 

 funnels. 



The alimentary canal is about 34 cm. long. It is composed 

 of 5 parts — pharynx, oesophagus, midgut, intestine, and rectum. 

 The pharynx is about 5 mm. long and 2 mm. in diameter, and 

 has thick muscular walls. It is held in position by means of 

 2 lateral mesenteries. The oesophagus is very much twisted, but 

 has a length of about 2.5 cm. when it is removed and straight- 

 ened out. Its walls are very much thinner than those of the 

 pharynx. The next part of the canal, which I have called the 



