BNTEROPNEUSTA FROM MADRAS. 125 



The dorsal surface of the trunk is marked by two submedian 

 ridges, which are correctly described by Spengel and Marion. 

 In the posterior region of the trunk, at some distance behind 

 the Ijranchial region, two similar ridges (due to the thicken- 

 ing of the longitudinal muscles) make their appearance on 

 the ventral side on either side of the median ventral groove. 

 These ridges become narrower posteriorly. The lateral 

 portions of the trunk — that is, the portions lying outside the 

 submedian lines — are thicker in front than behind. The 

 surface of the trunk is marked by transverse grooves and 

 ridges both above and below. The colour of the animal 

 agrees generally with that given by Spengel. The general 

 colour is white or yellowish white on the ventral surface, 

 which changes into yellowish brown on the dorsal, especially 

 in the branchial region. Irregular dark brown patches are 

 present on the dorsal surface of the proboscis and the collar. 

 The ridges between the transverse grooves are marked by 

 yellowish-brown pigment, especially on the dorsal side. 



The internal organisation agrees very closely with 

 Spengel's account. Spengel was able to see only the proxi- 

 mal portion of the vermiform process, having utilised the 

 anterior portion of the proboscis for longitudinal sections. 

 This, however, seems to be the only portion present. In one 

 large specimen examined by me the process was only a little 

 over y\=j- mm. in length. The dorso-ventral septuni of the 

 proboscis stretches much farther forwards than the process. 

 The vermiform process of this species is thus in a very 

 reduced condition. As pointed out by Spengel, the chon- 

 droid tissue of the proboscis skeleton is very highly 

 developed ; the posterior limbs of the skeleton reach to the 

 hind end of the collar. In the collar Spengel mentions a 

 posterior epidermal invagination, and in his figure of a 

 median longitudinal section he indicates a similar anterior 

 invagination. This latter I have found in my sections, and 

 one like it at the posterior end of the collar cord. They are 

 both of them depressions into the actual nerve-tissue, and it 

 is not clear to me why they are not called ueuropores (the 



