HARRIMANIA MACULOSA II3 



the ventral proboscis septum, a plate of the connective tissue core 

 wedges itself between two radial muscle plates, and reaches nearly to 

 the ectoderm. Into this plate there extends to a point considerably 

 beyond the anterior extremity of the proboscis complex a small but 

 very distinct tube with clear-cut lumen and wall of well-defined cubical 

 epitheloid cells. This tube is connected with the globus on its ventral 

 side and toward the anterior end, and is probably a blood vessel, 

 though the character of its wall as indicated above, contrasts sharply 

 with the usual enteropneustic blood vessels. This structure is not con- 

 nected with the notochord, hence is not homologous with the ' ver- 

 miform process ' of Schizocardium. Glomus well developed, though 

 the two halves not confluent excepting slightly antero-ventrally. 



The facts relative to the proboscis-coelom and its pores are as fol- 

 lows : I . As stated above, unpaired central cavity wanting, this being 

 replaced by the connective-tissue core. 2. The co^lom confined to the 

 extreme base of the proboscis and consisting of two wholly separate 

 lateral halves of equal size. 3. Posteriorly, each of these cavities 

 bifurcate, the two legs or pouches of each being placed, the one dorsal 

 to the other. 4. The ventral pouch on each side ends blindly, while 

 the dorsal ones open to the outside, each through its own pore, so 

 ^?i\. two proboscis pores are always present. 5. The proboscis pores 

 open very close in front of, sometimes actually into, the anterior 

 neuropore. 



Collar. — Dorsal nerve cord sometimes with and sometimes with- 

 out a distinct anterior neuropore ; throughout its length numerous 

 small, entirely closed cavities within its substance. ' Giant cells ' 

 present. No dorsal crest or dorsal ' nerve roots.' Periha^mal diver- 

 ticula not reaching forward quite to the anterior neuropore ; the 

 septum between them complete to their extreme anterior end, con- 

 taining only longitudinal muscle fibers. Dorsal blood vessels not 

 situated within this septum, but a sinus bounded by the nerve 

 cord dorsal ly, and by the walls of the periheemal diverticula ventro- 

 laterally. Collar coelom extending far into the neck. Peripharyn- 

 geal spaces apparently absent. Crura of nuchal skeleton reaching 

 into the pharyngeal region aitd overlapping two or three pairs 

 of branchial bars. Body of the skeleton also extending usually 

 far back, reaching nearly to the middle of the collar. The skele- 

 ton moderately strong, but the chondroid tissue not abundantly de- 

 veloped. Notochord consisting of two distinct parts: the anterior 

 pouch-shaped part corresponding to that found in all Enteropneusta, 

 and 2i posterior gutter-shaped part directly continuous with the Jirst 



