US IS 



^^^ ■ EDWARD S. MORSE ON 



left and terminates near the posterior .lorsal face of the first anterior occlusor Tl., .. 

 the gastro-parietal band (49 : l). In alcoholic specimens this band has a marked backwai^^ 

 flexure, due probably to the contraction of the coelomic walls. From this band as well 

 as from other bands, the genital products arise, to wliich further allusion will be made 

 The band is bluish white in color and is of considerable strength. When the coelomic 

 ca^^ty is crowded with genital products, a number of membranous strands, binding the 

 mass together, are seen running in various directions (49 -. -2) . The gastro-parietal bands 

 are distmct enough as to their main points of attachment, and the membranous strands 

 just alluded to appear to be proliferations from the edge of the gastro-parietal band 

 At 49:6 IS shown the appearance of the intestine at the point of attachment of the 

 gastro-parietal bands. From the posterior bend of the intestine, on the dorsal side, a band 

 runs back connecting with the posterior wall of the coelomic cavity. This band seems 

 to be split into several strands and is quite distinct from a genital band which appears in 

 folds ]ust above it (49: l) . Below this is a narrow band attached to the posterior bend of 

 the intestine and connected with the coelomic walls; 49: 3 represents a rough outline of 

 B. lamdlosa in longitudinal section in whicli attachments of these two bands are shown. 

 In the early stages one of these bands shows very conspicuously (50: 15) . I have called 

 this band ilio-parietal, following Blochmann. 



In T. septentrionalis (56: 2), a wide band stretches across the coelomic cavity 

 transversely, passing over the intestine, to which it seems to be attached anteriorly and 

 involving the nephrostomes. Huxley compared this band with the nephrostomes 

 suspended from it, to a landing net hanging in its frame. He was the first to call this 

 band the iho-parietal. From the posterior edge of this band and certainly below its edge 

 a narrow band arises whicli splits into one or more strands, and this band not only 

 supports the "accessory hearts of Hancock," but the genital products, either ova or 

 spermatozoa; for this reason they are called genital bands (56: 1, 2, 3). These bands, or 

 at least their edges, support a strongly cihated epithehum (59: i), and during genital 

 activity the edges become thickened by glandular growth (56:2,g.g). This same 

 thickening of the edge of the ilio-parietal band is seen in T. corecmica, Is will be shown in 

 discussing the genitalia. In T. coreanica, the ilio-parietal band, in which the nephro- 

 stomes are involved, surrounds the stomach, becoming narrower in that part connected 

 with the nephrostomes and sending out two narrower bands in front and laterally. Poste- 

 riorly it is connected with a median septum which runs back to the posterior coelomic 

 wall. A strong median septum runs forward from the stomach to the anterior coelomic 

 wall, and these two septa may be looked upon as the ventral and dorsal mesenteries 

 respectively (55:8). Other bands diverge from the stomach both lateraUv and posteri- 

 orly, and these are named, provisionally, ilio-parietal bands (59 : 9) . 



