364 EDWARD S. MORSE ON 



In T. sepfentrioiiii/is, the uephridia are suspeuded i'roiii the gastro-parietal liaml on t'ach 

 side of the intestine, with the nephrostomes opeinng toward the dorsal shell (56: 2) . This 

 figure represents the right nepliridium with a portion of the intestine and the (hvarirator 

 muscles. The band, by which the nephrostomes are held, stietches across the coelomic 

 chamber and adheres to the intestine as well. In 56: 1, is shcnvn the left nephridinm in 

 profile. The nephrostome is wide, and within, the surface is thrown into a number 

 of irregular folds which on one side gradually mei'ge into pa})illae. Two of these ai-e shown 

 more highly magnified, witliin which may be seen the ciliary ridge (56: -")■ The agaric- 

 like regularity of these folds, as figured by Hancock, in 7'. (■(ipKi-scrpcut'is, is not oljserved 

 in T. scpfciifrionafis, at least in its living state, and I may add also that Hancock represents 

 the nephrostomes as quite close together, while in 7'. sejjtentinoiKtJis they are widely sepa- 

 rated from each other, as may be seen in 60: 1, This peculiarity adds another distinction 

 justifying the separation of the two species. The body of the uephrichum has a rich brown- 

 ish-yellow color (39:9), and is marked by varicose ridges; the surface, more highly 

 magnified, shows very irregular luarkings, transverse to the long diameter of the tube 

 (56:26,2c). Tlie nepliridial tubes viewed in front through the coelomic wall (60: l,"i), 

 run nearly parallel and turning abruptly, pierce the wall and project beyond in tlie foi'm 

 of prominent nipples (56: 7). Dall (71) describes the external openings of the nephi-idia 

 in DalUna Jioridana as teat-shaped with very small orifices. Doubtless in related forms 

 this protuberant end will be found, though in 7'erehratalia coreanlca, as we shall see, it is 

 in the form of a simple slit in the parietes. The appearance of the orifice in the nephri- 

 dium of 7\ septentrlonalk, viewed directly in front, is shown in 56 : C The nipple is 

 nearly circular, the larger tUameter being vertical ; the opening is circular and an indica- 

 tion of a lozenge-shaped escutcheon is seen surrounding the orifice, this appearance arising 

 from muscle fibers which possibly control the orifice. The interior of the opening, as well 

 as the channel within, is strongly ciliated. It will be seen in 56: 1, 2, that a band, or bands, 

 quite separate from the ilio-parietal band, originate at the edge of the nephrostome and 

 run ventrally ; upon this is fomid the accessory vesicle as well as clusters of ova. This is 

 the genital band and is well show^n in 56: 1. In 60: 1, the attitude of the nephridia in 

 relation to the mouth and brachia is shown. In 56 : 4, 5, the appearance of the nephridia in 

 very young specimens is given. The flaring edge of the nephrostome instead of being 1am- 

 ellated has a distinct, thickened rim ; the rim of the nephrostome seems to be interrupted, 

 as if its attachment were Uke that seen in L. lejndula, that is, that the band, or wall to which 

 it is attached, forms part of the boundary of the nephrostome. In T. coreanica, viewed 

 from the dorsal surface (55: 8), the nephrostomes open obliquely backward. The inner 

 surface is marked by thin, sharp, radiating folds which in appearance suggest the actinoid 

 coral, Fungia (55: 9). The folds are vertically marked or plicated. A sHght constriction 



