vm, D, 4 



Wharton: Some Philippine Thalassemx 



255 



'~-t-Cint 



circular muscle, it seems very reasonable to assume that they are 

 more or less closely associated with the respiration of the animal. 

 The importance of the dermal muscle layer, as a means of 

 classification, will be discussed later. 



THE ALIMENTAKY CANAL 



The alimentary canal is about four times as long as the body. 

 For the first fourth, its course is definite, but the remainder 

 seems to vary a little in different individuals. As in most 

 worms the differentiation of the various parts of the canal is 

 so slight that it has been very diflficult to assign definite names 

 and functions to them. This form does 

 not seem to agree with any of the pub- 

 lished descriptions which are at hand. 

 The part of the canal from the mouth 

 to the beginning of the intestine has 

 been described differently in almost 

 every species. Reitsch calls it simply 

 "intestine buccal;" Spengel divides it 

 into pharynx, oesophagus, and crop; 

 Jameson speaks of the pharynx, oesoph- 

 agus, gizzard, and crop of T. neptunii; 

 Embleton divides this region of Echiu- 

 riis unicinctus into pharynx, crop, and 

 gizzard ; and Ikeda describes a pharynx, 

 oesophagus, crop, and midgut in T. 

 tsenoides. Moreover, this difference is 

 not simply a difference in names but in 

 the structure of the parts themselves. 

 For example, in Echiurus unicinctus, 

 the gizzard, which has very thick walls 

 of circular muscle, reduced epithelium, 

 and no glands, corresponds in position to the midgut of T. 

 tsenoides in which the epithelium is folded and glandular and in 

 which thin layers of both longitudinal and circular muscles are 

 present. 



In T. griffini three distinct regions can be made out in this 

 part of the alimentary canal. These may be called oesophagus, 

 crop, and midgut for want of better terms to describe them. 

 They are followed by the intestine and rectum. The oesophagus 

 is a straight tube about 1 to 2 cm. long and 2 mm. in diameter. 

 The epithelium is ciliated, and is slightly folded. The muscle 

 layer is rather thicker at the anterior end than in any other 

 part, but the difference is not great enough to justify speaking 



Fig. 3. Diagram of the inter- 

 nal organs of Thalassema 

 griffini sp. nov. pr, probos- 

 cis ; ne, nephridial sacs ; 

 oe», oesophagus ; cr, crop ; 

 mg, midgut ; int, intestine ; 

 c. int, collateral intestine ; 

 r, rectum ; d, diverticulum ; 

 at, anal trees. 



