HYDROZOA, 8CYPHOZOA, ACTINOZOA, VERMES WHITELEGGE. 373 



Gonosome : Gonangia ovate, borne on the front of a pinna at 

 the base of a hydrotheca 1*7 mm. high, 0'5 mm. broad in the 

 middle, and 0*3 mm. at the neck, which is about as high as broad, 

 surface with from 8 to 10 distinct annulations. Aperture square 

 with four membraneous opercular teeth. 



FAMILY PLUMULARID^E. 



AGLAOPHENIA CLAVICULA, sp. nov. 



(Plate xxiii., figs. 4, 5, 6.) 



Trophosome : Hydrocaulus simple, monosiphonic, attaining to 

 3 cm. in height, the terminal 1-3 cm., consists of an undulate 

 tubular extension indistinguishable from similar tubular growths 

 which constitute the hydrorhiza. Hydrocladia alternate, one to 

 each internode, arising from the front of the stem, from 2 '5 to 7 

 mm. in length, and about 0'5 mm. apart. Hydrothecse closely 

 approximate, 0*25 mm. in height and about 0*14 mm. in diameter. 

 The shape is urceolate with a slight constriction below the base of 

 the teeth. Margin with seven erect teeth, the median one is 

 evenly rounded at the apex, those at the sides are somewhat 

 acute. 



Intrathecal ridge distinct, extending transversely across the 

 basal portion of the hydrotheca. 



Lateral nematophores 0*1 mm. in length, 0'05 mm. in diameter, 

 slightly projecting beyond the margin of the hydrotheca ; aperture 

 elongate, opening upwards and inwards. 



Mesial nematophoreO'2 mm. in length, 0'05 mm. in its broadest 

 diameter, adnate to the hydrotheca to within O'l mm. of the sum- 

 mit of the central tooth. Hydrothecal internode with a short ridge 

 or fold opposite the basal constriction of the hydrotheca. 



Gonosome: Corbula closed, 2'5 to 3 mm. in length, and I'l mm. 

 in diameter; the first internode bears a normal hydrotheca. There 

 are from 8 to 12 pairs of adnate costae; each costa bears from 6 

 to 8 minute nematophores along its upper margin, and has a 

 modified hydrotheca at its base. In a median longitudinal line 

 on the upper surface are situated a series of from 8 to 10 elliptic 

 or elongate apertures with broad, flat, thickened margins, similar 

 to those figured by Allman in the Challenger Report.* 



These species exhibit two characters which are of great interest 

 from a morphological point of view. 



In the first place the apical portion of the stem is destitute of 

 the usual appendages ; at a short distance above the terminal 

 pinnules the nodes are also suppressed, and the stem becomes a 



* Allman " Challenger " Eeport Zool., vii., pi. xx., fig. 6. 



