92 PRONEOMENIA INSULARIS. 



After extending backward for about half its length the pharynx bends 

 abruptly upwards and unites with the stomach-intestine. In the angle thus 

 formed is placed the radula that is considerably shorter than in the foregoing 

 species. The teeth also are much smaller though of somewhat similar shape 

 and judging entirely from longitudinal sections there are probably not less than 

 twenty-eight transverse rows with at least twenty-four teeth in each row and 

 possibly more. On the other hand the radular supports, in the form of several 

 transverse rods of compact connective tissue, are more highly developed. The 

 relation of the pharynx and the stomach-intestine are sufficiently shown (Plate 8, 

 fig. 4). The anterior coecum, the gut pouches, and the digestive cells are also 

 essentially like those of P. hawaiiensis and require no comment. 



In connection with the circulatory system there are no unique characters. 

 Every blood space was crowded with corpuscles, spherical in form, with dense 

 nuclei and cytoplasm, colorless after treatment with Delafield's haematoxylin, 

 and containing several refringent granules. 



In this species the brain is of medium size, its greatest diameter equaling 

 one eighth the average diameter of the body, and is situated some distance 

 behind the union of the pharynx and mouth. As usual three pairs of nerves pass 

 from its forward and lateral regions to the front part of the body, becoming lost 

 to view in the region of the cirri or more laterally among the body muscles. 

 The connectives passing backward are completely ensheathed in the anterior 

 pedal gland whose granular substance renders it very difficult to follow them to 

 their destination. It has been possible to trace the relatively large pedal fibres 

 to the pedal ganglia, and the lateral connectives to their position along the sides 

 of the body, but the labio-buccal connectives are exceedingly difficult to differen- 

 tiate. However with the aid of high magnification their course has been traced 

 beyond question to the ganglia situated on each side of the pharynx about the 

 level of the radular supports. Each is characterized by a much elongated spindle 

 shape, the connective uniting with its anterior end and the ventral commissure 

 attaching posteriorly. This latter nerve arches over the dorsal side of the radula 

 and otherwise presents the usual appearance. A dorsal buccal commissure, 

 subradular system, and labial commissure were not found. 



Immediately in front of the radula is a ridge of columnar cells that may 

 correspond to the subradular organ. In several sections it is also possible to 

 distinguish fibres that have the peculiar refraction of other undoubted nerves; 

 yet in spite of persistent effort it has not been possible to determine their relations. 



Three pedal commissures have been proven to exist and eight palliopedal 

 connectives, all with the usual relations. 



