248 The Philippine Journal of Science 1913 



midgut, is about 5 cm. long ; it runs backward from the end of 

 the oesophagus for about half its length, then turns on itself 

 forming a U, and runs forward again where it turns to the right. 

 The walls of this part are thicker than the oesophagus, but there 

 is no indication of any separation into crop and gizzard such as 

 is found in many other forms. The intestine as usual is com- 

 posed of two parts. The first part, bearing the collateral in- 

 testine, is about 10 cm. long, and is much wider than any other 

 part of the canal except the rectum. The second part is longer 

 and narrower than the first part, and is filled with small regular 

 pellets of sand. The rectum forms the last 15 mm. of the canal. 

 It is a sac-like organ about 8 mm. in diameter, and bears the 

 anal trees at its lower end. 



The vascular and nervous systems agree in almost every 

 respect with the typical forms of the genus. 



Thalassema formosulum Lampert. 



Thalassema formosulum Lampert, Zeitschr. f. wiss Zool. (1883), 39, 

 339; Shipley, Willey's Zool. Results (1899), pt. 3, 340. 



One individual of this species was collected by Mr. A. L. Day 

 near Catbalogan, Samar. It was brought up on a cable from a 

 depth between 10 and 24 fathoms. The bottom was of fine mud. 



The length of the preserved specimen is 4.5 cm., and its 

 greatest diameter is 18 mm. The proboscis is about 1 cm. long, 

 and forms a tube at the mouth. The body is slightly pointed 

 in front, while the posterior end is broad and flat with the anus 

 opening on a small projection. The body wall is very thin, and 

 is sparsely covered with small round white papillae which are 

 nowhere arranged in rings. 



The longitudinal muscles show 7 narrow bundles, the spaces 

 between the bundles being from two to three times as wide as 

 the bundles. On sectioning, the dermal musculature was found 

 to be unusually thick in proportion to the remainder of the body 

 wall. The longitudinal muscle was found to be continuous, 

 although it has the 7 thickenings which have been mentioned. 

 The muscle of the bundle is between two and three times as 

 thick as that of the region between the bundles. In all 3 layers 

 the muscle has an unusual lack of compactness ; the fibers, which 

 are very large as compared with other forms, being scattered 

 in a loose connective tissue which is full of small sinuses. The 

 ventral setae are long and hooked, with orange-colored tips. In- 

 ternally, they are attached to the body wall by strong radial 

 muscles, and their ends are connected by a powerful interbasal 

 muscle. 



