III.— PYEOSOMA SPINOSUM, HERDMAN. 



By George P. Farran, B.A. 



Through the kindness of Dr. Wolfenden, I have had an opportunity 

 of examining two specimens of Pt/rosoma, which had heen taken hy 

 his yacht, the Silver Belle, in February, 1906, off Cape St. Mary, 

 Portugal, at a depth of 200 fathoms. 



Both of these apparently belong to Pt/rosoma spinosum, which was 

 described by Herdman in 1888, from fragments of specimens taken by 

 the Challenger in the South Atlantic. 



These specimens, like those taken by the Challenger, were captured 

 in the trawl, though possibly during the ascent of the net, and lead 

 one to suspect that the species lives at or near the bottom in deep 

 water, a fact which would account for the comparatively few records 

 — viz., two from the Challenger (Herdman, 1888), one from the 

 Talisman (Perrier, 1886), and one — a very young colony — from the 

 Helga (Farran, 1906). The two colonies were approximately ecpial in 

 size ; they were preserved in formalin, and were in excellent condition. 

 The one figured, from which the measurements were taken, measured 

 85 centimetres in length by 19 centimetres in circumference, but was 

 capable of a considerable amount of extension without rupture. The 

 walls were 6 millimetres in thickness throughout the greater part of 

 their length, but thickened considerably at the closed ventral end, and 

 thinning away round the common cloacal aperture. The whole colony 

 was tapered gradually to the closed end, which was rounded off bluntly. 

 The open end had an irregular aperture of almost the full width of 

 the colony. Its edges did not show any trace of lips or diaphragm, 



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