532 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



According to the preceding data, we appear to be justified in concluding 

 that Promachocrinus kerguelemis spawns in the spring and reaches the end 

 of the c_ystid or prebrachial stage (indicated by the incipient and actual for- 

 mation of radial structures) in November- February that is to say, in midsummer. 

 Although_ so far as I am aware, no quantitative information is available, this 

 season, being the season of maximum illumination, must be the season of the 

 maximum abundance of the diatom flora and of the associated floras and faunas. 

 By April the radials show considerable growth, and in the following November 

 the IBrj appear. 



One year after the first appearance of the radial structures the radials form 

 a complete circlet about the calyx, except in the posterior interradius, where the 

 two posterior radials are separated by the radianal. They are found almost in 

 contact in August-January and just in contact in November- July. 



In April of the second year the radials are about two-thirds as large as the 

 basals, and in the following September-November they have become nearly as 

 large as the basals. 



The end of the second year finds the two posterior radials coming into contact 

 beneath the radianal, which occurs in September-January. 



By the following June, two years and a half after the completion of the cystid 

 stage, in the middle of the second winter of its existence, the pentacrinoid, judg- 

 ing from a comparison between the most developed individuals and the smallest 

 free living specimens, is fully grown and ready to discard the larval column. 



The following examples of the pentacrinoid stage of Promachocrinus ker- 

 guelensis have been studied: 



No. 1 (fig. 881, p. 533) : Dredged on November 9, 1902, at a depth of 385 meters. 

 Total length (distal portion of column missing) 1.1 mm. length of crown, 

 0.3 mm. 



The stem as preserved consists of seven columnals, of which the first is twice 

 as broad as long, with a projecting narrow girdle about the proximal margin; 

 the second is about as long as broad, with a similar prominent projecting girdle 

 near the proximal margin; the third is somewhat longer than broad, with a narrow 

 girdle just proximal to the middle; and the fourth and fifth are about twice as 

 long as broad, with a median girdle; the two distalmost columnals are crushed. 

 Prominent infrabasals appear to be present. 



The basals form a deep cup with slightly and regularly convex sides, which 

 is slightly higher than broad. 



The orals are about as high as the basals: their sides in the proximal half 

 are parallel, and the profile of the distal half, which is bent inward, is semicircular, 

 with a narrow median notch; bounded by lines running from the apex of this 

 notch to the proximal angles is a triangular area which is more or less flattened 

 from which the distal and lateral portions of the orals are bent outward at a 

 considerable angle. 



No. 2 (fig. 882, p. 533) : Dredged on November 9. 1902, at a depth of 385 meters. 

 Total length (distal portion of column missing). 2.3 mm.: length of crown. 

 0.3 mm. 



