592 PROCEEDINGS OF THE AMERICAN ACADEMY. 



The tentacles of the velum are usually alternately large and small, 

 but this arrangement does not obtain with absolute regularity. Their 

 number does not appear to be constant, but is in the neighborhood of 

 fifteen. The innervation of the tentacles presents a beautiful appear- 

 ance when impregnated with methylene blue. Figures 8 and 9 illus- 

 trate these nerves with different degrees of detail. From these figures 

 it may be observed that each large nerve passing to a tentacle breaks 

 up suddenly, at the base of its tentacle, into a great number of small 

 branches, which divide, anastomose and interlace throughout the 

 entire free portion of the tentacle. Such meshes as are formed are 

 usually much elongated parallel to the long axis of the tentacle. 

 These nerves of the velar tentacles are also granular in appearance, 

 and occasional small nuclei or cells occur in the course of the nerve 

 tlii-eads. Free nerve ends may be noted, but these must always be 

 considered in connection with the fact that in methylene-blue prepara- 

 tions little epithelium favorable for studying the general innervation 

 of the velar tentacles persists. In some instances small, darkly- 

 staining thickenings of the nerve ends may be seen projecting beyond 

 the border of the tentacles, or exterior to the network of nerves (Fig. 

 9, c). These may represent some form of nerve ending in the epithe- 

 lium of the velar tentacles. The elaborate innervation of the tentacles 

 suggests that many nerve endings may exist in them. 



The variation mentioned in the nerves supplying the ^'elum has no 

 doubt led to the apparently conflicting statements with regard to 

 the numbers of these nerves. In the specimens observed, only 

 branches of nerves of the left side of the body passed to the velum, 

 and these usually enter the velar muscle on the left side. A branch 

 of left nerve IV has been described which entered the velum slightly 

 to the right of a mid-dorsal line, but this case appeared to be excep- 

 tional. Nerve IV may send a branch directly to the velum, or a 

 branch may anastomose with that of nerve V on its way to the velum. 

 In Figure 7 branches of nerves VI and VII anastomose with the 

 Branch of nerve V passing to the velum. It is difficult to explain just 

 what these anastomoses mean. Nerve IV sometimes sends a large 

 branch to the velum, nerves V and VI usually send branches of con- 

 siderable size, but nerve VII seldom contributes largely toward the 

 innervation of the velum. The branch of left nerve IV indicated at 

 IVa in Figure 8 appears to be associated with the nerves of the velum, 

 but is actually entirely free from the velar muscle. I have frequently 

 observed a branch of left nerve IV ending in this manner in this region. 

 Variation no doubt occurs in this nerve branch, and it may therefore 



