14 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



Small plates (fig. 4c) sparingly scattered among towers. No hour- 

 glass-shaped deposits; no cups. Sole with numerous shallow cups, 

 typically with 4 perforations (fig. 4f). Small plates (fig. 4d) occur 

 rarely among cups. Ventral tube feet with well-developed end 

 plates and supporting deposits in form of curved rods and plates 

 0.11 to 0.15 mm in length (fig. 4e). Tentacles with larger curved 

 or straight rods and plates 0.130 to 0.225 mm in length (fig. 4g) 

 and smaller rods and plates 0.08 to 0.13 mm in length (fig. 4h). No 

 rosettes in tentacles. 



HoLOTYPE. — Complete specimen, total length 12.5 mm, greatest 

 breadth 9.8 mm. Located at Universitetets Zoologiske Museum, 

 Copenhagen, Denmark. 



Type-locality. — San Jose Island, Gulf of Panama, 25 fathoms, 

 collected Jan. 27, 1916, by Th. Mortensen. 



Paeatypes. — Thirteen specimens, total length 8-14.5 mm. 

 Locality and depository as above. 



Remarks. — This species is named in honor of the late Dr. Th. 

 Mortensen, whose Pacific Expedition of 1914-1916 contributed so 

 much to our knowledge of echinoderms. 



Lissothuria mortenseni is known from near the type-locality of 

 L. ornata Verrill but differs from that species in lacking rosettes from 

 the tentacles and hourglass-shaped deposits from the dorsal surface 

 of the body. 



Lissothuria deichmannae, new species 



Figure 5 



Diagnosis. — Dorsal scale covering complete. Deposits of dorsal 

 surface are hourglass-shaped deposits and flat plates; no towers. 

 Deposits of sole are larger heavily knobbed plates, which tend to be- 

 come 2-layered, smaller plates with knobbed margins, and hour- 

 glass-shaped deposits. Tentacles lack rosettes. 



Description. — Single specimen approximately half as broad as 

 long. Tentacles expanded, oral and anal apertures dorsally placed, 

 surrounded by numerous sharply pointed valves. Dorsal surface 

 covered by scales overlaid by thick integument packed with calcareous 

 deposits. Sole thin, with 2-3 rows of marginal tube feet. Midventral 

 radius with 1-2 rows of tube feet throughout, more crowded anteriorly 

 and posteriorly, but scattered at center of radius. 



Dorsal deposits (apart from scales) are hourglass-shaped deposits 

 and flat plates. No towers found. Hourglass-shaped deposits 

 variable in shape and size (fig. 5a), length ranging from 0.05 to 0.1 mm. 

 Some resemble cups with ventral projections; others are asymmetrical. 

 Flat plates of 0.18 mm average greatest length, with larger perfora- 

 tions near center (fig. 5e) ; some plates may occur in dorsal tube feet. 



