47 116 Proceedings of the Royal Irish Academy. 



body is very constant and characteristic. It gradually increases in size up to 

 the 15th setigerous segment, and then tapers towards the tail (PL XIII, 

 fig. 29c). The body thus seems to be inflated in the anterior region, re- 

 sembling that of Scalibregma infiatum. The body segments are narrow, and 

 not clearly differentiated. 



The head (fig. 29a, 29d) is pointed in front, swollen behind. Just behind 

 the narrow part of the head is a pair of laterally placed reddish-brown 

 kidney-shaped eyes, the pigment of which seems to be partially soluble in 

 alcohol. In front of, and on the outer side of, the eyes are the ciliated nuchal 

 organs. The individual segments composing the anterior part of the body 

 are not distinguishable, except by the appendages they bear. The dorsal 

 tentacles, each accompanied by a lateral cirrus placed externally, occur on 

 the segment in front of that bearing the first bundles of setae. The lateral 

 cirri, of which there are about 46 pairs, are situated as usual just behind and 

 above the dorsal setae. The anus (fig. 29e) is dorsal, bounded above by three 

 ill-defined papillae and below by a prominent lobe. 



In the anterior segments the setae, 5-8 in number, both dorsal and 

 ventral, are capillary. In the dorsal bundles there are a few very long slender 

 cylindrical setae, without any distinct neck or flattening of the blade. These 

 setae are about 1 mm. long. The ventral bundles sometimes have one or two 

 slender capillary setae. The remaining capillary setae in the dorsal division 

 and in the anterior ventral feet are shorter capillary setae, with flattened 

 blades and a distinct neck and curvature where the cylindrical shaft emerges 

 t'rorn the body-wall (fig. 29f). They are - 2-'3 mm. in length. There are only 

 capillary setae in the dorsal bundles. The position of the first crochets 

 in the ventral division is not constant, varying from the 15th to the 25th 

 segment. At first there are only 1 or 2 crochets in each foot, but in the 

 posterior region the arrangement is fairly constant, as shown in fig. 29b. 

 The dorsal division usually contains 3 long slender cylindrical setae, 

 alternating with 3 shorter thicker setae, with slightly flattened blades. The 

 ventral division contains 3 crochets alternating with short capillary setae. 

 The uppermost seta of the ventral division is usually a short capillary seta, 

 thicker and more flattened than the rest. 



The crochets (figs. 29g, 29h) are bifid at the tip, the two points forming 

 an acute angle. This is best seen in the ventral crochet. In the uppermost 

 crochet, and sometimes in some of the others, the point is simple, through 

 abrasion of the tip. The shaft of the crochet is longitudinally striated. A 

 distinct neck separates the shaft from the blade, and the latter is obliquely 

 striated. This applies to all the setae except the very long dorsal capillary 

 setae. The thick flattened setae in the middle and posterior dorsal divisions 



