24 



SIDONOPS ANGULATA. 



Sidonops angulata, sp. nov. 



megana, var. nov. 



Plate 12, figs. 1-8, 16, 17, 19, 20; Plate 13, figs. 1-12, 22-25; Plate 14, figs. 1-6, 16-22; Plate 15, 



figs. 1-4, 7-9, 11. 



Plate 12, figs. 11-15, 18, 21, 22; Plate 13, figs. 13-17, 21; Plate 14, figs. 7-9; Plate 15, fig. 10. 



Plate 12, figs. 9, 10; Plate 13, figs. 18-20; Plate 14, figs. 10-15, 23-30; Plate 15, figs. 5, 6, 12. 



I establish this species for four specimens obtained at three different sta- 

 tions off the coast of southern Cahfornia, in the vicinity of Santa Barbara Island. 

 Some of the amphioxes and also a few of the rhabdomes and clades of the telo- 

 clades are angularly bent, and to this character the specific name refers. Two 

 specimens from Station 2975 are identical. The other two differ from these and 

 from each other so much that it is necessary to recognize three varieties. In 

 the specimen from Station 2945, var. orthotriaena, the subcortical triaenes are 

 orthoclade, in the three others plagioclade. In the two specimens from Station 

 2975, var. megana, some of the anaclade-cladomes are large, while in the speci- 

 men from Station 4417, var. niicroana, all the anaclade-cladomes are small. 



Shape and size. One of the specimens of var. megana is more lobose, the 

 other more massive. The lobose specimen (Plate 12, fig. 19) has the shape of a 

 stout fan, 86 mm. broad, 75 mm. high, and 28-38 mm. thick. Rounded pro- 

 tuberances rise from its surface and give to the margin of the fan a somewhat 

 serrated appearance. On one side these protuberances attain a greater height 

 than on the other, and here the depressions between them in one place join, 

 leaving a part of the sponge, 11 mm. thick, suspended like a bridge between 

 them. The surface is rough, shagreened. The greater part of this roughness 

 is due to the presence of slight pit-like depressions which are about 1 mm. wide 

 and are close together. Apart from a few holes, about 1 mm. wide, which do 

 not seem to be oscules, no apertures visible to the unassisted eye occur. In a 

 few sheltered places remnants of a spicule-fur are observed. The massive speci- 

 men of this variety (Plate 12, fig. 20) has the shape of an inverted cone with a 

 strongly rounded margin. It is 77 mm. high. The largest and smallest trans- 

 verse horizontal diameters are 112 and 107 mm. respectively. There are a few 

 broad and low protuberances, chiefly on the margin of the upper, somewhat 

 concave face. From the base a digitate process, 25 mm. long and up to 14 mm. 

 thick, arises. The most exposed parts of the surface are smooth; the rest of it 



