1905.] siruxcuLiDs, etc. of the "skeat" expeditiox. 35 



species, though it might pos.siljly be referable to Th. jyilhicidum 

 Fischer, which is, however, a Western form. 



The muscles number 1 2 or 1 3, but some of them are so indistinct 

 as to make it impossible to be qtiite certain. The anal trees 

 are quite short, brown, tapering, and simple. IS'o other internal 

 features can be made out. The proboscis is 10 mm. in length as 

 compared with a body length of 40 mm., and in this agrees with 

 Fischer's species [cf. Shipley, Willey's Zool. Res. part iii. p. 351). 



Each ventral hook has an accessory hook of about the same size 

 lying close to it. 



20. Thalassbma decameuox, sp. nov. (Plate I. fig. 5.) 



Log. Chwaka, Zanzibar. 



Hctb. In sand. 



One specimen. 



This specdes is characterised by the presence of four pairs of 

 nephiidia, which are, however, small in this individual and only 

 slightly elongated. Two of them, moderately distant from each 

 other, lie behind the setie ; and the other two, much closer 

 together, in front of the setse. 



The body- wall is extremely thin ; internally it is possible to dis- 

 tinguish ten, fairly broad, but inconspicuous, longitudinal muscles, 

 which can also be seen from the outside shining through the skin. 

 The anal trees are long, broad and brown at the base, but soon 

 tapering and becoming transparent ; simple and not dendritic in 

 this individual. 



EXPLANATION OF PLATE I. 



Fig. 1. Fln/smsoma eviseeratum (p. 31). a. Papilla fvom the fi-oiit end of the body. 



h. Papilla from the hind end of the body. c. Hook. 

 Fig. 2. Thascolosoma vulgare, var. seleulcee (p. 31). a. Papilla from the introvert. 



h. Hook. 

 Fig. 3. Thascolosoma glaucum (p. 32). a. Dissection showing- internal anatomy. 



h. Papilla from the front end of the introvert. 

 Fig. 4. Phascolosoma wasini (p. 32). a. Dissection showing internal anatom.y. 



h. Papillae from introvert. 

 Fig. o. Thalassema decmneron (p. 35). a. Body laid open, to show nephridia, 



muscles, and anal trees, h. Skin from mid-body. 



G. On the Sipunculids and Eehiurids collected during the 

 " Skeat " Expedition to the Malay Peninsixhi. By 

 W. F. Lanchestee, M.A , Assistant Lecturer and De- 

 monstrator in Zoology in University College, Dundee *. 



[Received November 1, 1904.] 



(Plate II.+) 



This collection, which Mr. Sliipley kindly pitt into my hands 

 for detei-mination, contains 12 species of Sipunculids and 1 of 

 Eidiiurids ; the latter is a new form, as are also four of the 



* Communicated by the Secretaey. 

 t For explanation of the Plate, see p. 41. 



3* 



