GULF OF MEXICO 



395 



Genus 1 PENTAMERA Ayres 1852 

 Pentamera pulcherrima Ayres 



Pentamera pulcherrima Ayres, 1854, p. 200; Deichmann, 

 1941, p. 84. 



Diagnosis. — Small species, at utmost 10 cm. 

 long. Ovoid, with oral and anal ends upward 

 curved. Feet in five crowded bands. Color white 

 or dirty browTi with tentacles dotted with dark 

 pigment. Spicules two-pillared tables with oval 

 disk with four holes. Feet with large end plate 

 and curved supporting tables with two-pillared 

 spire, sometimes reduced. Type: Undoubtedly 



lost. Type locality: Charleston, S. C. Distribu- 

 tion: Common along the Atlantic seaboard, occa- 

 sionally reaching the coasts of New England. 

 Taken at Sabanilla, Columbia (U. S. National 

 Museum), and once reported from the coast of 

 Texas (J. Hedgpeth, letter). In the South it is 

 taken in shallow water where it lives buried in the 

 mud. In the northern waters it lives in deeper 

 water and is either washed up after storms or 

 dredged. Grave (1905) has reared it from eggs 

 taken with free swimming larvae in the plankton 

 around Beaufort, N. C. Some of these specimens 

 were kept alive for 3 years. 



Genus 2 THYONE Oken 1815 



KEY TO THE SPECIES KNOWN FROM THE GULF OF MEXICO 



1. Spicules in skin tables with large disk; supporting tables in feet with enormous, reticulated spire. Apparently spicules 

 preserved throughout the animal's life 1. Thyone mexicana Deichmann, p. 395 



1. Spicules in skin tables with disk of normal size; supporting tables with normal spire, or a low reticulum 2 



2. Disk of tables thick, oval, with four small holes; spire two-pillared with two large clusters of spines; sometimes a handle 



is present on the other side of the disk making a transition to the buttons found in other genera. 



2. Thyone pseudofusus Deichmann, p. 395 



2. Disk of tables of normal thickness, with four large and up to four smaller marginal holes. Spire often delicate w-ith 



feeble spines 3 



3. Tables usually with squarish disk, and tendency to have four pillars in the spire; supporting tables with complex, low 



spire. Large species, 12 cm. or more; greenish or brownish 3. Thyone briareus (LeSueur), p. 395 



3. Tables oval or squarish, with weakly developed two-pillared spire. Supporting tables delicate. Seems never to attain 

 its full size in American waters. Possibly a guest from the eastern Atlantic 4. Thyone inermis Heller, p. 397 



1 Thyone mexicana Deichmann 



FIO. 67: 1-3 



Thyone mexicana Deichmann, 1946, p. 1, text tig. 1. 



Diagnosis. — Large form 10 cm. or more; re- 

 sembles the type species T. fusus from the north- 

 eastern Atlantic, but the spicules appear to be 

 retained throughout life and the feet are more 

 clumsy on account of the tall, thimble-shaped 

 spire on the supporting tables. Color mottled 

 brown. Spicules tables with several circles of 

 holes and knobbed edge; spire with two pillars 

 and occasionally three to four. Feet wilh end 

 plate and numerous supporting tables with huge, 

 reticulated spire. Type: U. S. National Museum. 

 Type locality: Sugarhouse Bend, Barataria Bay, 

 Grand Isle, Louisiana. Distribution: So far 

 known from the coast of Louisiana and Texas, in 

 tidepooJs, down to few fathoms. 



2 Thyone pseudofusus Deichmann 



Thyone pseudofusus Deichmann, 1930, p. 168, pi. 14, 

 figs. 6-9; 1941, p. 107. 



Diagnosis. — Small species 4 to 5 cm. long. 

 Spicules tables with oval disk with thick rim, two- 



piUared spire with clusters of spines on top and 

 frequently a handle on the inner side. Type: U. 

 S. National Museum. Type locality: Yucatan, 

 25 fathoms. Distribution: Known from Yucatan, 

 Florida, Tobago, British West Indies, and coast 

 of Brazil. In Yucatan 18 specimens were taken 

 in the same haul so the species may possibly have 

 direct development with the larvae settling down 

 close to the parents. 



3 Thyone briareus (LeSueur) 



Hololhuria briareus LeSueur, 1824, p. 161. 

 Thyone briareus Deichmann, 1930, p. 165, pi. 13, figs. 

 5-7; 1938, p. 134; 1946, p. 3. 



Diagnosis. — Large robust form, 12 cm. or more, 

 with numerous tube feet which give an almost 

 hairy aspect to the animal. Skin soft due to the 

 scarcity of spicules; color dark greenish or bi-own; 

 sometimes faded in alcohol. Spicules scattered 

 tables with mostly squarish disk; often tliree to 

 four pillars in spire; feet with large end plate and 

 elongate supporting tables with low irregular 

 spire composed of several rods. Type: Lost. 

 Type locality: Florida. Distribution: From 



