REPORT ON THE ECHINOIDEA MORTENSEN 291 



end tooth. This form, which occurs only between the scrobicular 

 spines on the upper side of the test, usually bending inward over the 

 base of the large spine muscles, is quite evidently a specialization of 

 the small globiferous pedicellariae; indeed, transitional forms some- 

 times occur; one might even be tempted to regard them as abnor- 

 mal small globiferous forms, but their fairly regular occurrence in the 

 places designated both in this and in other species of Stylocidaris rather 

 necessitates regarding them as a special form of pedicellariae, appar- 

 ently characteristic of the genus Stylocidaris. They are usually few 

 in number and are found on by no means all specimens. The tri- 

 dentate pedicellariae (pi. 80, fig. 5) are numerous, fairly conspicuous, 

 up to 1 mm. in length of head, with the stalk of very variable length, 

 sometimes quite short, sometimes as long as 4 mm. The valves are 

 very slender, widely gaping, and joining only near the end. The 

 blade is narrow and deep, usually with a series of cross beams in the 

 lower part; the edges are very finely serrate. 



The spicules of the tube feet are simple, slightly spinous rods; in 

 the intestinal wall there are numerous small irregular plates, or some- 

 times only a few more or less regular triradiate spicules. 



In color the primary spines are whitish; the secondaries have a 

 more or less conspicuous greenish or reddish longitudinal stripe. The 

 test is whitish, only the apical system having a darker, greenish- 

 brown or reddish tint, especially on the inner part of the genital plates 

 and on the periproct. 



Notes. — In the intestine I have found only detritus with unidenti- 

 fiable remains of bottom organisms. 



The small size of the eggs (only 0.1 mm. in diameter) and of the 

 female genital openings would seem to indicate that this species has 

 pelagic larvae. 



Abnormalities are not rare, especially in the ambulacra; in one 

 specimen ocular II and genital 1 are broken up into smaller plates 

 (fig. 196) ; in another genital 1 has two pores. A specimen from sta- 

 tion 5410 is remarkable in having Amb. I double in its whole length 

 (pi. 59, fig. 3) . A parasitic gastropod (Stylifer?) sometimes is found in 

 the primary spines, which are then usually transformed into globose 

 galls, rarely growing out to anything like their normal length. The 

 spines also are often overgrown with foreign organisms, mollusks (Ore- 

 pidida), serpulids, barnacles, etc. In two specimens a very interest- 

 ing case of regeneration was observed; one or two of the oral primaries 

 have for some reason or other been lost, and instead of a new primary 

 spine and tubercle some secondary spines and tubercles have been 

 formed within the space of the original primary areole. 



Some of the numerous specimens collected by the Albatross differ 

 from the form which I regard as the typical one in that their primary 



