102 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



Type. — Holotype, AHF no. 29, 5 paratypes. 



Type locality. — Station 633-37, San Gabriel Bay, Espiritu Santo 

 Island, L. Calif., 18 fms., March 6, 1937. 



Distribution. — Widespread in the Gulf of California and as far as 

 Panama. 



Depth. — From 10-35 fms. 



Specimens examined. — The type and 5 specimens from the following 

 Velero stations : 



244-34. Bahia Honda, Panama, 30-35 fms., February 21, 1934, 1 speci- 

 men. 



554-36. Parallel to Angel de la Guardia Island, east side, 10 fms., 

 March 8, 1936, 2 specimens. 



562-36. North of San Esteban Island, L. Calif., 20-70 fms., March 10, 

 1936, 1 specimen. 



633-37. San Gabriel Bay, Espiritu Santo Island, L. Calif., 18 fms., 

 March 6, 1937, 1 specimen. 



719-37. Consag Rock, L. Calif., 10-25 fms., March 24, 1937, 1 speci- 

 men. 



Remarks. — The material shows to perfection how impossible it is to 

 give an exact description of the general appearance of most holothurians. 

 Two individuals are well expanded with tapering bodies, one is con- 

 tracted to a short Pentacta-\\kt form, and two resemble slightly deformed 

 oranges. The spicules, however, are completely identical, and a closer 

 study of the anatomical features, calcareous ring, etc., showed that the 

 specimens also in these respects are alike. 



T. mexicana is closely related to the type species but differs distinctly 

 in the shape of the spicules. The extremely deep baskets and the large 

 strongly knobbed buttons alone are sufficient to distinguish the present 

 species from all other related forms known from the Panamic region. 



Genus 8. THYONE Oken, 1815 



Thy one Oken, 1815, p. 351. 



Anaperus Troschel, 1846, p. 60 (partim). 



Diagnosis. — Small to medium-sized forms (rarely more than 10 cm. 

 long, many species smaller). Body thin skinned with numerous nonre- 

 tractile fairly delicate feet, most numerous ventrally. Tentacles 10, the 

 2 ventral smaller. Calcareous ring with long posterior prolongations on 

 the radials. 



