98 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



Spicules an external layer of concave plates, often with a delicate 

 reticulum across the hollow surface; an inner layer of knobbed, irregular 

 buttons, and larger plates with knobbed surface, sometimes transformed 

 into large convex bodies. Feet apparently devoid of end plate ; walls with 

 short, broad, perforated supporting rods. Introvert and tentacles not 

 examined. Color of the preserved specimens white. 



Tj;^^.— Holotype, AHF no. 28. 



Type locality. — Station 850-38, Cape San Francisco, Ecuador, 15 

 fms., February 23, 1938. 



Distribution. — Known only from the type locality. 



Depth. — From 15 fms. 



Specimens. — The type. 



Re?narks. — The type represents undoubtedly an immature individual. 

 On account of its small size and its rigid skin it was almost impossible to 

 dissect, and no attempt was made to study the tentacles and introvert. 

 The inner organs were poorly preserved, and nothing can be said about 

 the stone canal and Polian vesicle. The musculature is feebly developed, 

 and the intestine and respiratory trees form a structureless mass; a well- 

 developed muscle stomach could, however, be seen. The calcareous ring 

 is highly reminiscent of the one figured by Sluiter for javanica (see text 

 figure 2), and it is of course remotely possible that the present species has 

 previously been described from the East Indies. As the various earlier 

 descriptions are rather unsatisfactory, as also the figures hitherto pub- 

 lished, it has been deemed wiser to designate the unique individual to a 

 new species. 



L. nina differs distinctly from both L. nova and L. panamensis in its 

 calcareous ring as well as in its spicules. It cannot be confused with any 

 other species at present described from the Panamic region. 



Genus 6. PENTAGTA Goldfuss, 1820 



Pentacta Goldfuss, 1820, p. 177.— H. L. Clark, 1923, p. 416. 

 Colochirus Troschel, 1846, p. 64. (Type species. — C. quadrangularis 



Troschel.) 

 Cercodemas Selenka, 1867, p. 343. (Type species. — C. anceps Selenka.) 

 Diagnosis. — Body with more or less flattened ventral side with the 

 tube feet arranged in 3 bands ; dorsal side vaulted with feet of different 

 size, often as large papillae, frequently scattered in the interambulacra. 

 Around the base of the introvert and the anus the ambulacra form thick 



