286 



TORRE Y. 



[VOL. II. 



spirals of the lophophore there are one and one-half to two, 

 and a correspondingly smaller number of tentacles (170-200), 

 Fig. r, A, B. In the strength of its longitudi- 

 nal muscles (Figs. 2, 3) it departs ivomP.Buskii 

 and even surpasses P. architecta, resembling 

 the latter species in the possession of a 

 specialized ridge in the digestive tract (though 

 this does not pass into the groove that Andrews 

 describes), in the structure of the nervous sys- 

 tem, lophophore organ and tube, in habit, and 

 in the possible separation of the sexes. 



It is not my intention to enter into a full 

 and detailed anatomical description of Phoro- 

 nis, which the labors of Benham and Cori have 

 rendered largely unnecessary. But a few 

 words on some points may not be out of place. 



In one of the Puget 

 Sound specimens sper- 

 matogonia and sperma- 

 tocytes were found 

 packed around the blood 

 vessels in the aboral regions of the body, 

 but no spermatozoa nor ova. The aboral 

 ends of all the Humboldt specimens were 

 wanting, so it was impossible to deter- 

 mine whether they were monoecious or 

 dioecious. In one nephridium three ova 

 were found unaccompanied by sperma- 

 tozoa ; the first polar body was forming 

 in one. As there was no sign of sperma- 

 tozoa in these eggs, it is probable that in 

 this species fertilization takes place either 

 externally or within the nephridium. It 

 is quite possible that the sexes may 

 be separate, or ova and sperm may be produced by the same 

 individual but not simultaneously. 



The blood corpuscles have a conspicuous yellow color and 

 measure 10-15^ in diameter. 



'N 



FIG. 3. Cross-section 

 of one longitudinal 





FIG. 4. Cross-section of the 

 oesophagus of P. j>aci_fica, 

 showing the ridge, its base in 

 contact with the median lon- 

 gitudinal blood vessel. 



