A MONOGRAPH OF THE EXISTING CRINOIDS 257 



One of the specimens from Menado Bay, Celebes, is large with 22 arms; eight of 

 the IIBr series are 4(3+4) and one is 2. There are three IIIBr 2 series, all internal. 

 The cirri have 18-19 segments of which the longest are about as long as broad or slightly 

 broader than long, and the outer are broader than long. The second specimen is 

 similar. There are three IIBr 2 series, the other seven being 4(3 + 4). The longest 

 cirri have 19 segments of which the longest are broader than long and the outer are 

 from half again to twice as broad as long. The third specimen is much broken. 



A specimen from Siboga station 254 was described as a new species under the name 

 of Pachylometra helius in the following terms: 



The centrodorsal is of moderate size, flattened hemispherical or thick truncated 

 conical, 6 mm. in diameter at the base, 3 mm. across the flat dorsal pole, and 4 mm. 

 high. The cirrus sockets are arranged in 10 evenly spaced columns of 2 or 3 each. 



The cirri are about XXV, 23, about 28 mm. long. The first segment is short, 

 those following gradually increasing in length to the fifth and sixth, which are the 

 longest, between one-third and one-half again as long as broad. The segments following 

 very slowly decrease in length so that those in the distal third of the cirri are about as 

 long as the distal width. In the distal third of the cirri the median portion of the distal 

 dorsal edge of the segments is somewhat swollen, this swelling on the last five or six 

 before the penultimate becoming a blunt subterminal dorsal tubercle. The opposing 

 spine is prominent, short, sharp, terminal, and directed obliquely forward. 



The ends of the basal rays are visible as large rhombic tubercles in the angles of the 

 calyx. 



The radials are entirely concealed. The IB^ are very short, broadly V-shaped, 

 with the proximal and distal edges parallel ; the lateral thirds of the proximal and distal 

 borders are slightly produced. The IBr 2 (axillaries) are very short, nearly or quite 

 three times as broad as long, rhombic in shape with concave sides and truncated lateral 

 angles, the lateral edges being about as long as those of the IBri. The lateral edges and 

 all but the median portion of the proximal edge are very slightly produced. The 

 synarthrial tubercles are low and broad, scarcely evident. The contour of the proximal 

 portion of the animal is broadly rounded, as in 0. septentrionalis. 



The 26-28 arms are 125 mm. long and have a smooth dorsal profile. The IIBr 

 series are 4(3+4) and the IIIBr series are 2, internally developed. The dorsal portion 

 of the basal segments of P D is visible between the IIBr series. 



In another specimen from Siboga station 254 the IIIBr series are 2, internally 

 developed except for one which is situated by the side of an internal IIIBr series. In a 

 specimen with 28 arms eight of the IIBr series are 4(3+4) and two are 2; the cirri are 

 from 25 to 34 mm. long with 20-23 segments. The three other specimens are small 

 with 17, 19, and 20 arms. 



The specimen from the Danish Expedition to the Kei Islands station 8 has 28 

 arms 150 mm. long. Three postradial series are regular with 6 arms each, there being 

 two IIBr 4(3+4) series and two internally developed IIIBr 2 series. One postradial 

 series has 7 arms, there being three IIBr 2 series. The IBr axillary is followed by two 

 ossicles side by side, but these bear a single very broad ossicle with two distal angles 

 which bears 3 arms side by side. 



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