360 



THE ORIGIN OF VERTEBRATES 



Gegenbaur, in his picture, draws a straight tubule passing from every 

 goblet among the fine canaliculi of the chitin. He says they are 

 difficult to see, except in the case of the larger goblets. The tubule 

 from the larger goblets is most conspicuous, and is in my sections 

 always tortuous, never straight, as represented by Gegenbaur. A 

 special branch of the appendage-nerve passes to these organs, and 



V '--clit 



B 



Fig. 144. — A, A Goblet from 

 one of the Branchial Sense- 

 Organs of Limulus (ch.t., 

 chitinous tubule) ; B, Surface 

 View of a Portion of a Bran- 

 chial Sense-Organ. 



Fig. 145.— The Endognaths of Limulus 

 pushed out of the way on one side 

 in order to show the position of 

 the flabellum (fl.) projecting to- 

 wards the crack between the pro- 

 somatic and mesosomatic carapaces. 



upon the fine branches of this nerve groups of ganglion-cells are seen, 

 very similar in appearance to the groups described by Patten on the 

 terminal branches of the nerves which supply the mandibular organs. 

 At present I can see no mechanism by which the goblets are extruded 

 or returned into place. In the case of the Capitellidse, Eisig describes 

 retractor muscles by means of which the lateral sense-organs are 



