ritter: octacnemus. 245 



aud decidedly to the right, by a large elliptical, plain mouth. The wall 

 of the funnel is very delicate. I have seen no cilia in any part of it. 

 Within the funnel were observed six or seven rather distinct deep-orange 

 pigment spots. 



Owing to the differences between my results and those reached by 

 Moseley and Herdmau relative to the branchial sac, the question of the 

 endostyle is especially important. Both these observers having failed to 

 find the branchial stigmata, based their conclusions to a considerable 

 extent on what they supposed to be the endostyle. Herdman, however, 

 recognized that the structure believed by him to be this or^an was not 

 the same as that held by Moseley to be such. It is now certain that 

 neither Moseley nor Herdman saio the true endostyle. 



Having found, in the manner above detailed, that the cavity opened 

 into by removing the dorsal patch of visceral wall, as shown in Figure 3, 

 must be the true branchial cavity, I proceeded to carefully remove the 

 food material and refuse by which this cavity was completely tilled.^ Hav- 

 ing cleaned this out thoroughly, examination of the floor of the chamber 

 discovered the groove indicated at e. n., Figure 4, Plate 2. Eoth from 

 its position and structure, (though in this latter respect there was con- 

 siderable disguising) tliere could be no doubt that the true endostyle 

 had been come upon at length. By dissecting out the piece containing 

 the organ, aud examining it Avith more care, it was found that the 

 typical endostylar structure could be made out, aud, further, that 

 anteriorly the organ connected in the usual way with the peripharyn- 

 geal band (Fig. 7, en. andjj. h. b., Plate 2). The two lips of the organ 

 were unusually far apart, and their irregulai-ity in outline and minuter 

 composition gave to the organ as a whole something of the peculiarities 

 ah'eady indicated as characterizing both the dorsal lamina and the 

 peripharyngeal band. And here, as in all the parts of the branchial sac 

 where cilia would be expected, no trace of them could be found. JTie 

 entire apjoaratus^ if is probable, has lost its original respiratory function, 

 and has become devoted to the nutritive office ; and the peculiarities of 

 structure of various parts, notably of the stigmata, dorsal lamina, endo- 

 style, and peripharyngeal band are, it would seem, due in large measure 

 to this change of function. 



Whether the branchial wall has actually become digestive or not, I 

 am unable to say with certainty. However, from the great amount of 

 food material contained in the cavity, much of which was in various 



1 I was able to identify with approximate certainty in the stomach contents, 

 portions of a copepod, a schizopod, a pycnogonid, a tanais, and a young fish. 



