120 Mr Thomas A. Huxley on a Hermaphrodite and 



treinity, which lies in immediate proximity to the oesophagus 

 (fig. 4), and receives the insertion of the lateral longitudinal 

 muscles of the body. Superiorly, as has already been said, the 

 axis divides into four branches, one of which enters the stem of 

 each branchia and forms its skeleton and support, sending 

 lateral processes into each of the pinnules. These, however, 

 are much more delicate, and are composed of oblong particles 

 set end to end ; somewhat like the axis of the tail of an Ascidian 

 larva. All this branchial skeleton, as one might term it, is 

 invested by a continuation of the general parietes of the body, 

 which adheres closely to the outer side of the stem and 

 pinnules, but leaves a space on their inner side. In this space 

 lies the so-called " blood"-vessel, with its green contents. It 

 does not fill the space, but lies loosely in it ; the interval be- 

 tween it and the walls of the filament being, I suppose, in 

 continuity with the perivisceral cavity.* 



The whole of the internal surface of the branchiae is pro- 

 vided with long, close-set, vibratile cilia, while nothing of the 

 sort is visible externally. The end of the stem has a very 

 peculiar structure. It is somewhat enlarged by the develop- 

 ment within its walls of a number of elongated granular 

 masses of about T ^o 5 i ncn i n length, entirely made up of 

 very minute, strongly refracting granules, which, when 

 pressed out, become rapidly diffused and dissolved in the 

 surrounding water. These bodies were not confined to the 

 ends of the branchial stems, but similar aggregations existed at 

 the ends of many of the pinnules, and were also very regularly 

 developed in little elevations seated upon the sides of the stem 

 in front of the base of each pinnule.f 



A limentary Canal. — The oesophagus leads into a pyriform, 

 more or less marked, dilatation or crop, provided with thicker 



* The skeleton of the branchiae of the Serpulacea has been well and care- 

 fully described by De Quatrefages in his valuable memoir " Sur la circula- 

 tion des Annelides," Annales des Sciences Naturelles, 1850; and that of Sabella 

 unispira by Grube, so long ago as 1838. See his memoirs " Zur Anat. und 

 Physiologic der Kiemenwurmer." 1838. 



t Are the peculiar rounded whitish granular patches which occupy a 

 similar position on the arms of Comatula of a corresponding nature, or are 

 these really testes ? I have never been able to find developed spermatozoa 

 in them, nor anywhere else in Comatula. 



