289 



totally wanting in the posterior ends of the specimens at hand. The 

 tentacles are bright yellow. There are only few wheel-papillae, which 

 in the three dorsal interambulacra make a single line. In the ven- 

 tral interambulacra wheels are nearly totally wanting, only in the 

 anteriormost end a few wheel-papillae may be found. The body-wall 

 is rather thin and in the "head"-less fragments quite transparent. 



There are twelve tentacles each with six pairs of digits, and at 

 the base of the tentacles there are some few orange spots resembling 

 eyes. The calcareous ring (Fig. 57. 5) consists of 12 pieces of which 

 all the radiais are perforated for the nerves. A cartilaginous ring 

 is wanting. There are ca. 15 polian vesicles and a single stone- 

 canal. The madreporite (Fig. 57. 3-4) is of somewhat varying shape, 

 distinctly different from that in albatrossii. The retractor-muscles 

 are well developed, but united with the body-wall by a mesentery- 

 like tissue. The alimentary-canal has a large loop and on the me- 

 senteries there are ciliated funnels. These are distinctly smaller 

 than the funnels in albatrossii, measuring not more than ca. 

 150 ju (Fig. 57. 2). In balsam-preparations the shape of the fun- 

 nels in pacifica and albatrossii is rather difficult to ascertain, for 

 which reason they may seem alike, but a dissection under a rather 

 high magnification clearly shows the differences. 



The wheels measure 50 — 80 ju in diameter. They have normally 

 six spokes, but wheels with a varying number of spokes are found 

 (Fig. 57. 1). A varying number of spokes in Chiridota-v/hQe\s was 

 found by Ohshima in albatrossii and by Dendy in Ch. gigas. 

 Rods are often nearly quite wanting and usually present only in 

 the anteriormost end of the dorsal side. They are rather varying 

 in shape (Fig. 57. 7), usually being bent, with enlarged ends. The 

 rods in the digits (Fig. 57. 8) are not so much different from those 

 in the tentacle-base (Fig. 6) as in albatrossii. Neither in the long- 

 itudinal muscles nor in the polian vesicles or in the gonads any 

 calcareous deposits are found. 



The sexes appear to be separate. The gonads are branched 

 and the genital-duct opens on a little wart-like papilla closely be- 

 hind the dorsal tentacles. 



Chiridota pacifica is nearly related to albatrossii and lœvis. From 

 lœvis it differs distinctly in having rods in the anterior end of body, 

 in the shape of the madreporite and in that of the ciliated funnels. 



Vidensk. Medd. fra Dansk naturh. Foren. Bd. 85. 19 



