190 SYNOPTIC COLLECTION. 



(No. 359, b, d), the narrow points of the star radiating 

 downward toward the ambitus when they become some- 

 what obscure only to reappear on the ventral side (No. 

 359, b) in the form of perforated bands which reach to 

 the mouth. Between these bands the interambulacra 

 are set in, the different areas and the individual plates 

 composing them varying greatly in shape and size. 



The mouth (No. 359, b) is at the anterior end with its 

 lip, while the anal disc at the posterior end (No. 359, a, 

 test of a younger specimen than the others) is perfectly 

 preserved. Below this anal plate there is another with 

 three openings on either side. In the sunken area at the 

 top are four openings. 



HOLOTHUROIDEA. 



We know nothing of the ancient ancestral Holothuroids 

 excepting by the minute hard parts, spicules, wheels, 

 anchors, etc., which are preserved in the rocks. 

 These occur no farther back than the Carbonic age 

 (Zittel). They throw little light upon the phylogenetic 

 history of the group, and therefore we must turn to the 

 primitive forms living to-day. 



Among the deep-sea Holothuroids are the Elasipoda 

 which retain the characters of the larva in the adult 

 stage more than any other members of the class. 

 Accordingly in describing the adult we are giving the 

 more essential larval characteristics. 



Generally speaking, the body is distinctly bilateral 

 (PI. 360, figs. 1-4, Elpidia verrucosa The'el. and Scotoph- 

 anes murrayi Theel), while its walls are provided with 

 simple spicules of few rays. The dorsal part of the body 

 extends in front, causing the mouth to turn towards the 

 ventral side (see figs. 2, 4) instead of being terminal. 

 The anus is dorsal in position (fig. i) or terminal as in 

 Scotophanes (fig. 4). The ventral surface is flattened, 



