GULF OF MEXICO 305 



KEY TO THE SPECIES AT PRESENT KNOWN FROM THE GULF OF MEXICO 



Based Mainly on Easily Recognizable External Characteristics 



With suction disk at posterior end of body; commensal in bivalve moUusks - M alacobdella grossa 



Without suction disk; not commensal in bivalves 2 



Mouth posterior to brain; proboscis not armed with stylets 3 



Mouth anterior to brain; proboscis with central stylet and usually with two or more pouches of accessory stylets.. 9 



Head without lateral longitudinal grooves 4 



Head with lateral longitudinal grooves 6 



Posterior end without slender caudal cirrus 5 



Posterior end with long caudal cirrus; head acutely pointed Zygeupolia rubens 



Body small, white; posterior end slender Tubulanus pellucidus 



Body when mature usually 30-150 mm. long; red or yellowish red; posterior end broad and flattened . 



Carinoma tremaphoros 



Body slender, rounded; head with two to eight pairs small ocelli Lineus socialis 



Body flattened in intestinal region ; head without ocelli 7 



Lateral margins rounded in intestinal region; not adapted for swimming; color red or rosy Micrura leidyi 



Lateral margins in intestinal region thin; adapted for swimming; color either pale or black 8 



Color whitish, pale yellow, or rosy Cerebratulus lacleus 



Color black Cerebratulus ater 



Proboscis with central stylet only and no accessory stylets; parasitic on crabs Carcinonemeries carcinophila 



With two or more pouches of accessory stylets; not parasitic 10 



Proboscis with four or eight pouches of accessory stylets; only one pair of ocelli Paranemerles biocellata 



Proboscis with two pouches of accessory stylets ; head with more than one pair of ocelli 11 



Ocelli numerous, extending posteriorly beyond head Zygonemertes virescens 



Ocelli limited to head 12 



More than two pairs of ocelli 13 



Only two pairs of ocelli 15 



Ocelli in a single row on each side of head ; blood corpuscles red A mphiporus cruentatus 



Ocelli in several groups or irregular rows; blood nearly colorless 14 



14. Central stylet of proboscis rounded at both ends and slightly constricted in the middle Amphiporus ochraceus 



14. Central stylet truncated at both ends; not constricted in the middle Amphiporus texanus 



Yellowish, without spots of dark pigment Tetrastemma candidum 



Body small, cylindrical ; color variable ; irregularly spotted with brown 16 



Body short and firm; ocelli large, those of the same side not coimected by band of pigment Oerstedia dorsalis 



Body soft, yellowish; the two ocelli of same side connected by band of dark pigment Tetrastemma vermiculus 



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SYSTEMATIC DESCRIPTION OF SPECIES 



The following pages contain abbreviated de- 

 scriptioos of the species at present known from the 

 Gulf, based mainly on easily recognizable external 

 characteristics. The geographic range, as given, 

 indicates the limits of the species insofar as at 

 present known and should not be interpreted as 

 implying that the species will not later be found 

 elsewhere. Outline drawings of each of the species 

 have been published by Coe (1951a). 



Order 1 PALEONEMERTEA 



Family TUBULANIDAE 

 Tubulanus pellucidus Coe, 1940, 1943 



Carinella petlucida Coe, 1895. 



The minute worms belonging to this species 

 may be recognized by their slender, white bodies 

 and by the absence of both ocelli and longitudinal 



grooves on the head. Length when mature 10 to 25 

 mm., width 1 mm. or less. 



The worms live in delicate, cellophane-like 

 tubes among algae and other growths in the 

 intertidal zone and below to a depth of at least 

 20 meters. Recorded from southern New England 

 to northern Florida, also Pensacola, Fla., and 

 presumably occur elsewhere along the Gulf coast. 

 Found also from Monterey Bay to San Diego, 

 Calif. 



Family CARINOMIDAE 

 Carinoma tremaphoros Thompson, 1900; Coe, 1943 

 Body pale reddish or yellowish, with broadened 

 posterior end which is without caudal cirrus. 

 Head broad, without ocelli or longitudinal grooves. 

 Length when mature 30 to 150 mm., width 2 to 5 

 mm. The worms burrow in mud, sandy mud and 

 clay, or live beneath stones in the intertidal zone 



