GULF OF MEXICO 401 



Family 2 PSOLIDAE 



KEY TO THE GENERA KNOWN FROM THE GULF OF MEXICO OR LIKELY TO OCCUR THERE 



1. Dorsal side with numerous tube feet and scales covered by a layer of complex spicules, hour-glasses, towers, curved 



plates, etc 1. Thyonepsolus H. L. Clark, p. 401 



1. Dorsal side without tube feet; scales naked or covered by a varyingnumberof grains or cups, or both 2. fsoius Oken, p. 401 



Genus 1 THYONEPSOLUS H. L. Clark !90l type locality and Tobago, British West Indies, 



Thyonepsolus braziliensis Theel b"*^ "^ ^^ '^ » small inconspicuous species it may 



occur much more widespread. In shallow water, 



Thyone braziliensis Th6el, 1886a, p. 15, fig. 7. attached to rocks or seaweeds. Nothing is known 



Thyonepsolus braziliensis Deichmann, 1930, p. 192, pi. about its life; even the color is not known though 



21, figs. 1-6; 1937, p. 173. -^ ^^^^ j-j^^j^ j^ ^^^.-^j^^ ^^^ ^^^^ ^^ ^^^ closely 



Diagnosis. — Small species, few cm. long, with related form known from the Panamic region. 



7 to 10 scales between oral and anal scales. Plates In Tobago several small individuals were taken 



in outer layer of dorsal side small, incomplete; from the same spot indicating that the develop- 



hour-glass shaped bodies relatively simple; towers ment is direct, but it is doubtful whether the eggs 



present in varying numbers, obviously a juvenile are carried around in depressions on the mother's 



character. Plates in sole with almost smooth back as is the case in T. nutriens H. L. Clark, 



even margin; tentacles with delicate rods and from the Californian waters. 



rosettes. Type: Museum of Comparative Zo- The genus with its three species is restricted to 



ology. Type locality: Porto Seguro, Brazil. the American waters, and the chances are that 



Distribution: As far as known only taken at the T. braziliensis also exists in the Gulf of Mexico. 



Genus 2 PSOLUS Oken 1915 



KEY TO THE SPECIES KNOWN FROM THE GULF OF MEXICO OR LIKELY TO OCCUR THERE 



1. Dorsal scales covered by grains and small, regular cups [3. P. complicatus Deichmann, p. 402] 



1. Dorsal scales covered by grains but no cups 2 



2. Few scales (2-4) between oral and anal scales. Grains few, large and ultimately fused with the scales, forming large 



protuberances 1. P. tuberculosus Th^el, p. 401 



2. Several scales (up to 6-7 scales) between oral and anal scales. Grains of moderate size. 



2. P. operculatus Pourtalfes, p. 401 



1 Psolus tuberculosus Th6el 



Psolus tuberculosus Th6el, 1886a, p. 13, pi. 1, fig. 5; 

 Deichmann, 1930, p. 186, pi. 20, fig. 3. 



Diagnosis. — Small form, sole up to 3 cm. long; 

 huge oral valves; anus surrounded by two circles 

 of small scales ; up to four scales between oral and 

 anal scales. Feet restricted to the lateral ambu- 

 lacra on the ventral sole. Spicules dorsally grains 

 which increase enormously and finally fuse with 

 the scales forming huge, blunt protuberances. 

 Sole with perforated plates often two holes larger 

 than the rest. Type: Museum of Comparative 

 Zoology. Type locality: Sand Key, 500 fathoms. 

 Distribution: The waters around Florida, Tor- 

 tugas, and Campeche Bank, Mexico. Usually 

 about 100 fathoms (95-135 fathoms); the type 

 appears to have come from exceptionally deep 

 water. The species is closely related to Fisher's 

 P. macrolepis from Hawaii and Ludwig's P. 



diomedeae from Gulf of California to Ecuador and 

 the Galapagos Islands. (See Deichmann, 1941, 

 p. 149.) 



2 Psolus operculatus (Pourtales) 



Cuviera operculata Pourtalfes, 1868, p. 127; 1869, p. 359, 

 361. 



Psolus operculatus Deichmann, 1930, p. 187, pi. 20, figs. 

 1-2. 



Diagnosis. — Small form, sole up to 4 cm. long. 

 Resembles P. sqttamata (D. & K.) with thin, 

 imbricating scales, distinct oral valves, and up 

 to seven scales between oral valves and anal scales ; 

 feet along margin of sole with a few at the ends of 

 the odd ambulacrum. Spicules dorsally grains, 

 lacking in very young individuals. Sole with 

 heavy, four-holed buttons, with knobbed margin, 

 increasing in number with age. Type: Museum 

 of Comparative Zoology. Type locality: Sand 

 Key, Florida, 120 to 125 fathoms. Distribution: 



