56 CAULOPHACUS SCHULZEI. 



then abruptly. Its distal part bears nmnerous fairly large spines, its proximal 

 part fewer and smaller ones. Sometimes this part of the ray is nearly smooth. 

 Exceptionally the proximal ray is reduced or hypertrophied. When reduced 

 it is 7-40 ;u long, more or less cylindrical, as thick throughout as the normal 

 proximal ray at its base, and terminally rounded. A hypertrophic proximal 

 ray observed (Plate 11, fig. 13) was 150 ti long, considerably thickened in the 

 middle, attenuated to a rather sharp point, and densely covered with large 

 spines. It measured at the base 16 ^ and at its thickest point 25 ix in transverse 

 diameter. Another still more hypertrophic one in all respects resembled the 

 (opposite) distal ray. 



The lateral rays are similar to the proximal ray, but more frequently smooth 

 in their basal part. They are 80-157 ix long, and 8-18 y. thick at the base. 



The lateral rays of the same spicule are usually fairly equal. But in one 

 quite abnormal pinule which I found in the large specimen D they were very 

 unequal. In this remarkable spicule two adjacent lateral rays were hyper- 

 trophic, covered with long spines, and similar to the distal ray of an ordinary 

 pinule, whilst the other two laterals were normal and the spinulation of the 

 distal ray so much reduced that it resembled the (normal) proximal ray. 



I measured a good many pinnies of four different specimens (B, C, D, and E). 

 The results of these measurements are tabulated on p. 57. Specimen E, which 

 was taken for detailed study because it appeared to be a part of a specimen 

 larger than any of the nearly complete ones, was too fragmentary to allow of 

 a distinction between its dermal and gastral faces. The dermal and gastral 

 pinules of this specimen are therefore not distinguished in the table. 



From this tablp the following conclusion concerning the differences in the 

 dimensions of the pinules can be drawn. There is, in specimens of similar 

 dimensions (B and C), a not inconsiderable variation in the dimensions of the 

 pinules, particularly the length of the distal ray. In the large specimen D all 

 the rays of the body-pinules attain a greater thickness and the proximal and 

 lateral rays also a greater length than the corresponding rays of the correspond- 

 ing pinules (dermal and gastral) of the small specimens B and C. The rays 

 of the dermal pinules are thicker at the base than the corresponding rays of 

 the gastral pinules of the same specimen. This applies also to the maximum 

 thickness of the distal ray with its spines in specimens C and D, but not in B. 

 The distal rays of the gastral pinules attain a considerably greater length than 

 the corresponding rays of the dermal pinules of the same specimen. The other 

 rays are in some specimens longer in the dermal, in others longer in the gastral 



