STROPHOMENIA SCANDENS. Ill 



three pairs of nerves arise from its anterior borders and are distributed to the 

 various structures of the atrial and body walls. From its lateral margins the 

 lateral, pedal, and labio-buccal connectives arise side by side. The lateral 

 present the usual appearance as is also true of the pedal whose union with the 

 pedal ganglia is marked by a well-developed enlargement. In nearly all cases 

 if not invariably the labio-buccal ganglia of the Solenogastres are located near 

 the openings of the paired ventral salivary glands when these exist, and since 

 in the present species these are situated far back the connectives imbedded in 

 the muscular pharyngeal wall are characterized by a relatively great length. 

 The ganglia imbedded in the wall of the pharynx give rise to three conomissures 

 and to the subradular connectives. The dorsal and ventral buccal commissures 

 are sufficiently indicated (Plate 6, fig. 6) to require no farther comment. In 

 one specimen, possibly both, a well-developed ganglionic enlargement occurs 

 on the ventral commissure and may correspond to the buccal ganglion, the other 

 larger ganglion with which it is in close proximity and from which the subradular 

 system is connected representing the labial. From this last named nerve mass 

 another commissure passes ventral to the alimentary canal and in its course 

 gives rise to two nerves which pass backward for a short distance and then 

 become lost in the tissues of the pharynx. 



As has been noted a typical subradular sj^stem is present in P. hawaiiensis. 

 In Limifosso7- talpoideus it holds the customary position, but ganglia are appar- 

 ently entirely absent. In one specimen of Strophomenia scandens very small 

 masses of ganglion cells seemingly represent the subradular ganglia of which 

 no sign exists in the other specimen. In this species no well-defined subradular 

 organ occurs hence the ganglia are perhaps in a state of degeneration. 



Owing to the compar-atively small size of the latero-pedal and pedal com- 

 missures they are not readily followed yet in certain places they have been 

 traced in dissections and sections, so that so far as may be judged they exhibit 

 no unusual features. 



In the posterior part of the body the relations shown (Plate 13, fig. 2) exist. 

 As there indicated the lateral and pedal ganglia are united by two strong con- 

 nectives, and posteriorly give rise to several branches that pass backward and 

 become lost in the somatic musculature. From the middle of the suprarectal 

 commissure a nerve arises that has been traced to the base of the dorso-terminal 

 sense organ. This last named structure (Plate 32, fig. 9) is protruded above 

 the general level of the cuticle. As indicated the cells are slender, naked, and 

 rest upon a small accumulation of what are probably ganglion cells. Muscle 



