BY W. M. BALE. 793 



species may be readily distinguished by it. The corbula (which 

 sometimes exceeds one-fourth of an inch in length) is closed above, 

 but the sudden narrowing of its component leaflets towards the 

 base leaves openings, across which project the lateral spines, 

 corresponding to the processes which in some species bear hydro - 

 thecee, but which here support only 2-4 sarcothecae. 



AGLAOPHENIA PHYLLOCARPA, n.sp. 



(Plate XXL, figs. 9-10). 



Hydrocaulus polysiphoiiic, pimise alternate, one on each internode, 

 both series springing from the front. Hydrothecae lying parallel 

 with the pinna, very large, elongate, sub-cylindrical ; a slight fold 

 or rudimentary intrathecal ridge near the base on the side next 

 the pinna ; aperture oblique, with eleven nearly equal claw-like 

 incurved teeth, one median, and five on each side, back deeply 

 sinuated next to each of the lateral sarcothecae, and with a broad 

 rounded lobe between, adnate to the pinna. Hydrothecal internode 

 narrow, with 3 transverse folds, one opposite the fold in the 

 hydrotheca, one at the base of the lateral sarcothecae, and one 

 midway between. Mesial sarcotheca very short, projecting out- 

 wards from the pinna and the basal part of the hydrotheca, free 

 part conical, canaliculate. Lateral sarcothecse canaliculate, pro- 

 jecting outwards and extending beyond the hydrotheca-margin, 

 free part conical, directed forwards, slightly upwards, or down- 

 wards, sometimes abruptly recurved so as to point towards the 

 back of the pinna, and away from the hydrotheca at a right angle. 

 Cauline sarcothecse on the front of the stem, two at the base of 

 each pinna, the lower larger. 



Gonangial pinna with 3 or 4 short distinct joints at the base, 

 bearing only sarcothecae. Corbula large, consisting of about 10 

 pairs of alternate ribs, expanded into very large leaflets, each of 

 which is attached by its proximal margin to about the middle of 

 the next leaflet behind ; the distal half of each leaflet forming a 

 large free expansion bordered with canaliculate sarcothecae ; each 



