J2 University of California Publications in Zoology. [Vol.6 



fact thai jusl as the largesl 6's of a are somewhat nearer the 

 distal than the 1 >:i-~;i 1 end. so seemingly the Largest &"s of a' are 

 somewhat nearer the distal ends of these axes; and the same ap- 

 pears to be true for the other orders as well. 



One other se1 of closely related facts is observable: the in- 

 dividual branches of any generation are arranged in the same 

 plane bu1 on opposite sides of the axis, and the new ones of the 

 two sides come in in alternate fashion. This is well illustrated 

 in Sgures 13 and 11. Figure 12 may seem to contradict this 

 statement, but the contradiction is only apparent, it being due 

 to the obliquity of the tentacle-axis to the line of vision. 



Worthy of note finally is the fact that the branches of the 

 several generations along the same side of any axis are in gen- 

 eral in a line, this line being somewhat nearer the edge of the 

 axis that looks toward the center of the tentacular circlet. 



Since the tentacle number is perhaps the must distind differ- 

 ential character between the two species, it would be instructive 

 to make a comparison of these organs in all the points shown 

 above to he subjecl to rules of multiplication, to ascertain 

 whether specific differences might not he found in sonic of these 

 as well as in the number of the tentacles themselves. 



There is little doubt that still more extended study of the 

 two species with reference to other organ systems would bring 

 out other specific differences. For the present, however, the 

 test and tentacle differentials must stand as their identifying 

 marks. But in addition to these two structural features of rec- 

 ognizable systematic value, there are a few others without such 

 significance that still deserve particular attention. 



Intestinal Tract. 



In the intestinal tract (PL 8, fig. 3), the pronounced 

 rectal bend, the obscurity of the differentiation of the stomach 

 from the intestine proper, the circumscription of the liver. /., 

 and its wide duct opening into the stomach, and the "lacteal" 

 system, Ic.s., are noteworthy. The mantle adheres very closely 

 to tin' viscera, especially to the intestinal tract. From this fact 

 and the fragility of the intestinal wall, it is somewhat difficult 

 to expose the organs uninjured. When this is accomplished one 



