BRYOZOA OF THE PHILIPPINE REGION 265 



cases. The avicularian umbo is almost perpendicular to the zooecial 

 plane and often the photograph gives only an incomplete idea of its 

 form and of size. 



Affinities. — This species differs from Mucronella (Petraliella) 

 thenardi Borkpatrick, 1888, in the presence of large distal spines and 

 in the absence of a large trifurcated, frontal spine. The ornamenta- 

 tion also is very different. It differs from Petralia laccadivensis 

 Robertson, 1921, in the presence of large distal spines. 



Biology. — The specimens from Jolo (20 fathoms) were in reproduc- 

 tion and fixation on February 15, 1908. The larva fixes itself on an 

 alga or on a small nulliporc. The zoarium then develops into free 

 lamellae. The ornaments of the shield increase with the depth of 

 the water. It is easy to see the progression on our figures. The 

 avicularian umbo is little salient at Jolo (20 fathoms), it increases at 

 Romblon (37 fathoms) it becomes very large at Tinagta (230 fathoms) 

 and acquires an enormous development at Simaluc (340 fathoms). 

 It appears therefore as an organ of oxygenation. Our specimens 

 were dead. 

 Occurrence. — 



D. 5137. Jolo Light, Jolo; 6° 04' 25" N.; 120° 58' 30" E.; 20 



fathoms; S. Sh. 

 D. 5162. Tinagta Island; 5° 10' N.; 119° 47' 30" E.; 230 fathoms; 



S. brk., Sh. crs.; 11.6° C. 

 D. 5179. Romblon Light, Romblon; 12° 38' 15" N.; 122° 12' 



30" E.; 37 fathoms; hard S.; 24.2° C. 

 D. 5574. Simaluc Island, north of Tawi Tawi; 5° 30' 45" N.; 



120° 07' 57" E.; 340 fathoms. 

 D. 5577. Mount Dromedario, Tawi Tawi; 5° 20' 36" N.; 119° 

 58' 51" E.; 240 fathoms; crs. S.; 12.4° C. 

 Coty pes. —Cat. Nos. 8017-8019, U.S.N.M. 



PETRALIELLA ECHINATA. new species 



Plate 27, figs. 1-6 



Description. — The zoarium encrusts nullipores without any free 

 lamellar expansion. The zooecia are distinct, separated by a deep 

 furrow, elongated, enlarged distally; the frontal is convex, punctured 

 with small widened tremoporcs in the midst of which small hollow 

 rods appear. The shield bears distally 6 large very long spines, 

 laterally two small salient avieularia, and before the aperture an 

 enormous avicularian umbo \<iy robust with large oblique mandible 

 and garnished with long hollow spines which give it a fantastic aspect. 

 The aperture is semielliptieal, transverse; the proximal border bears 

 a small lyrula and two small cardelles far apart from each other; the 

 peristome is thin and little visible. The ovicell is hyperstomial, 

 buried in the distal zooecium, very globular and formed of an oloc\ -t 

 surmounted by a fcremocyst with very small pores. 



