492 PROF. P. M. DUNCAN ON THE GENUS DIBBHOPALUM. 



scantier on the body. A second form of body-spicule has a less 

 decided curvature and but one globose end, the other being a 

 mere rounding of the cylindrical body. The spinulation resembles 

 that of the first type (PL XXIX. fig. 35). A third is longer than 

 the others, is bent more or less like a boomerang, has a globose 

 process at one end, and a narrow, cylindrical, and rounded ter- 

 mination at the other (PI. XXIX. fig. 36). The spinulation is 

 scanty on the body. There are intermediate shapes, and on some 

 there is a large spinule, in particular, on the cylindrical body (PI. 

 XXIX. fig. 37). These spicula are placed without order on the 

 surface of the coral in one layer, and are not very close. Length 

 rinr ^° Tiro" inch, thickness Yibu m ch. 



The long acuates, straight or sometimes slightly bent, project 

 well beyond the other spicula, and were covered with sarcode. 

 Their bases, rounded off and very minutely spinulate, are as thick 

 as one of the curved spicula just noticed ; they slope gradually 

 to a sharp point, and their axial canal is very manifest near the 

 base (PI. XXIX. figs. 32, 33). The radiating spicula are very 

 numerous and are arranged in bundles, the faintly enormispinu- 

 late heads of the spicula being close together and surrounding 

 the stout long and large acuates. The shafts of the spicula are 

 slightly swollen in the first third, so that they are more or less 

 fusiform, and the point suddenly becomes sharp, like a straight 

 sword. The shafts project upwards and slightly outwards, and 

 their points form a circle around the acuate spicule and tolerably 

 close to it (PI. XXIX. fig. 31). The heads of the spicula (length 

 Y^-g-to y^jj inch) are remarkable in shape ; there is a cylindrical 

 swelling with a short neck, and then there is a projecting end, 

 which is longer than broad, cylindrical, and rounded. An exces- 

 sively delicate and scanty spinulation is seen on the cylindrical 

 part and also on the rounded end (PI. XXIX. fig. 39). There 

 are no other spicula. The sarcodic structures enveloped the 

 whole, and were stretched out to the tops of the long acuates ; 

 there was a definite basal membrane. 



It is evident that this form is closely allied to the first species I 

 have described, from which it is distinguished by the shape of the 

 deeply-seated spicula and the direction of the enormispinulates. 

 It is possible that these distinctions may be racial ; but, under 

 existing circumstances, it is best to separate the forms specifically. 



The first species I have named Dirrhopalum Carteri, and the 

 second Dirrhopalum hystrix. 



