8 THE VOYAGE OF H.M.S. CHALLENGER. 



teristics. The oiial vesicles arc of moderate size, with irregularly distributed csecal 

 appendages, some of which are simple and others much branched, and which seem 

 usually to l)ear at their apex only a single minute ciliated funnel. In front of the 

 external openings of the segmental organs are two small hooked sette. There is only 

 a single i)air of segmental organs, which have at their extremity a folded and Avrinkled 

 vesicle. 



There was only a single contracted specimen about 40 mm. long and 15 mm. 

 broad. 



Habitat.— ll.M.i>. "Porcupine," Station 77, 1869; lat. 60° 34' N., long. 4° 40' E.; 

 560 fathoms. 



In some other species, namely in Thalassema mobii, GreefF,^ and Thalassema vegrande, 

 Lampert," the longitudinal musculature consists, as in this case, not of a number of 

 separate strands, Ijut of a continuous sheath. These two species above mentioned, 

 however, possess three pairs of segmental organs, and are therefore readily tlistiuguishable 

 from Thalassema facx. A single pair of segmental organs is characteristic only of 

 the latter and of Thalassema gigas, Max Miiller, which was found at Trieste, and is not 

 identical with this species. 



4. Thalassema haronii, Greeff. 



Thalassema haronii, Greeff, Die Ecliiuren (Gephyrea armata), Nova Acta Acad. Caes. Leop.- 

 Carol., Bd. xli. pars ii., No. 1, pp. 151, 152, Taf. vi. figs. 63, 64, 1880. 



Owing to the imperfect preservation of the single specimen, only a very incomplete 

 examination of the internal organs was possible. The proboscis was torn away. Greeff 

 found the species at Arrecife on the Canary Island Lanzerote, near the shore, among lava 

 blocks and debris. Of the real colour of Thalassema haronii, which GreeflF describes as 

 dark green with longitudinal stripes of xiolet, there was no longer any trace in the 

 yeUowish-brown specimen of the Challenger Exjaedition. On the other hand, however, 

 the two forms, found in such different places, agree in the following characters. 



The whole body is covered with small papillse. Each of the two pairs of segmental 

 organs has at its extremity a funnel. The anal vesicles have the form of two long tubes, 

 bearing on their surface short tree-like branches, which to the naked eye look Uke tufts, 

 and which possess terminal ciliated funnels. The longitudinal musculature of the body- 

 waU is arranged in from twenty to twenty-three strands. 



Habitat.- — Bahia, September 1873, 7 to 20 fathoms. 



The anatomical structure of the Challenger specimen so closely resembles that of 

 Greeff's species that I have no hesitation in identifying the two forms. 



' R. Greeff, Die Echiuren (Gepbyrea armata), Nova Ada Acad. Caes. Leop.-Carol., Bd. xli. pars ii.. No. 1, 

 p. 152, 1880. 



- K. Lampert, Ueber einige neue Thalassemen, Zdtaclw.f. wiss. ZooL, Bd. xxxix. p. 341. 



