68 PKOCEEDINGS OF THE NATIONAL MUSEUM vol.72 



Genus SIPHONOPORELLA Hincks, 1880 



SIPHONOPORELLA DUMONTI, new species 



Plate 7, Figure 4-7; text Figure 9 



Description. — The zoariiim is free; the fronds are cylindrical, bifur- 

 cated, rarely lamellar. The zooecia are distinct, separated by a deep 

 furrow, very elongated, rectangular; the mural rim is salient, finely 

 crenulated; the cryptocyst is deep, flat, granular. The opesium is 

 oval, little elongated; the polypidian tube is broad, salient, eccentric, 

 the avicularian zooecia are long, narrow, provided with a polypidian 

 tube; the mandible is large, spatulated. There is a salient tubercle 

 in each of the interzooecial angles. 



, r^ . [^0 = 0.30 mm. 

 Measurements. — Opesmm-^, „ „^ 



^ Uo = 0.20 mm. 



. iLz = 0.60 mm. 

 Ziooeciau „ „„ 



Us ==0.36 mm. 



n 



o 



E 

 Fig. 9.— Siphonopoeella dumonti, new species. A-C. Different aspects of the 



i, OPERCULAR VALVE. IN A THE SCLEKITE OF THE VALVE IS EXACTLY SUPERPOSED ON 

 THE EXTERIOR SCLERITE OF THE ECTOCYST. D. THE TWO PORTIONS OF AN AVICULA- 

 RIAN MANDIBLE. THEY ARE UNITED BY TWO STRONG LATERAL SCLEEITE3. E. AN 

 ORDINARY ONYCHOCELLARIUM, X 85 



Structure. — The internal structure is that of a simplified Stegano- 

 porella; there is only an oblique and short polypidian tube. The 

 opercular valve is simple, as those of Membranipores, and isolated 

 from the mural rim. It is inserted exactly into the ectocystal 

 sclerite which forms the aperture. 



The B zooecia have also a polypidian tube, but their opercular 

 valve is transformed into a true mandible of a size altogether equal 

 to that of the cryptocyst and of the same form. When it is lowered 

 it is exactly bordered by the mural rim. It has a mandibular struc- 

 ture very close to that of Steganoporella. In Lahibpora the differen- 

 tiation is complete, for here the B zooecia are transformed into true 

 interzooecial avicularia. 



Afinities. — This species differs from SipJionoporella granulosa in its 

 free zoarium, its rectangular zooecia, and the much smaller zooecial, 

 dimensions. The dimensions of the opercular valve are quite 

 variable. 



