398 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



as is often observed in material of different age. walls of feet with perforated rods, with or without 



More surprising is his statement that argillacea a third arm. Introvert with rosettes; tentacles 



possessed small gonads, but he may have mistaken with heavy rods in stem and delicate ones in the 



some lobes of the respiratory trees for these organs. terminal branches. Type: Possibly in Germany. 



r^ A •rtrvr.ivTirDti ~ Type locality: Fernando do Noronhas, Cuba. 



Genus 4 THYONERIA nom. nov. -r-.- ■^  r^ ^ ^r , rr^ 



Distribution: Cuba, Yucatan, fortugas, and 



New name for Semperia cognaia Lampert 1885. Biscayne Bay, Florida. Shallow water down to 



Thyoneria cognata (Lampert) few fathoms depth. H. L. Clark reports it at 



„ . , J * .ooc cT Biscayne Bay, from soft bottom in patches of 



Semperia cognata Lampert, 1885, p. 67. ^ ^ ? i- 



Thyone cognita Deichmann, 1930, p. 169, pi. 15, figs. 1-4. eelgrass. 



Thrione cognata H. L. Clark, 1933, p. 115. Deichmann, _ _ 



1938c p 134 ' ' f Genus 5 THYONELLA Verrill 1872 



Diagnosis. — Large form, 14 cm. long, fairly Remarks. — The genus was established, rather 



delicate, spindle-shaped, often oral and anal ends casually, by Verrill for Pour tales' Colochirus 



turned up. Tentacles 10, of equal size. Feet in gemmata. The name has been discarded by most 



double rows and scattered interambulacrally. authors, but it seems to be the only one suitable for 



Calcareous ring tubular, with distinct tails and gemmata. The diagnosis has been enlarged so it 



tall, narrow interradials. Spicules numerous takes in the members of Thyonacta Deichmann 



elongate plates with mostly two rows of holes and and provisionally Theel's Thyone pervicax which 



a varying number of smaller, button-like holes has become homeless after the name Thyone has 



with up to four holes. End plate in feet small, been restricted to the species with delicate tables 



almost rudimentary except in young individuals; in the skin. 



KEY TO THE SPECIES OF THYONELLA KNOWN FROM THE GULF OF MEXICO 



1. Tube feet numerous, covering the entire body as slightly conical warts. Small form, 7 cm. long; curved, rigid body. 

 Color white with brown spots, or light brown 3. Thyonella pervicax (Th^el), p. 399 



1. Tube feet in distinct double rows along the ambulacra, and scattered in the interambulacra but not covering the surface 



uniformly. Large forms, 15 cm. long. Color mottled gray or brown 2 



2. Cups in outer layer star-shaped, with four central holes and eight large marginal teeth. Mottled gray 



1. Thyonella gemmata (Pourtalfes), p. 398 

 2. Cups in outer layer ring-shaped, with four small marginal holes in the corners; marginal teeth small and blunt. Uni- 

 formly grayish brown 2. Thyonella sabanillensis (Deichmann), p. 399 



1 Thyonella gemmata (Pourtales) 



Colochirus gemmata Pourtalfes, 1851, p. 11. 

 Thyone gemmata Deichmann, 1930, p. 177, pi. 17, figs. 

 1-3. 



Diagnosis. — Large species, 15 cm., spindle- 

 shaped, often somewhat curved; feet in double 

 rows along the ambulacra and scattered in the 

 interambulacra, cylindrical except toward the 

 ends where they tend to become papilliform. 

 Color brownish-grayish mottled. Spicules exter- 

 nally flattened baskets with eight broad teeth and 

 four central holes; an inner layer of four-holed 

 buttons more or less regular and knobbed, with 

 tendency to become more irregular with age, with 

 holes reduced and surface undulated. Feet appar- 

 ently without end plate; walls stifl"ened by thick 

 perforated rods; in papillae triangular plates or 

 short tri-armed rods. Introvert with rosettes, and 

 small spectacle-shaped rods. Tentacles with 



heavy rods with small holes. Type: Undoubtedly 

 lost. Type locality: Sullivan Island, S. C. Dis- 

 tribution: Like Thyone briareus it seems to be one 

 of these species which is restricted to the Gulf of 

 Mexico and the Atlantic seaboard. It is known 

 from Yucatan, Texas, Florida, and South 

 Carolina. Also reported from near Woods Hole 

 but seems not to be permanently established so 

 far north. As far as known, always dredged from 

 a few fathoms depth. 



The records from Maine and Barbados are 

 omitted as they undoubtedly refer to individuals 

 which have been mislabeled. The species appears 

 to live buried in mud, and it is apparently one of 

 the most common species in the Gulf. Like so 

 many other of the larger species it is practically 

 unknown as young. The smallest individuals I 

 have seen measured 4 cm. in length but in strongly 

 contracted condition. 



