Thalassema papillosum (Delle Chiajej, a forgotten Echiuroid Gephyrean. 437 



of the proboscis, the cephalic part of the blood vascular system is 

 incomplete; in sections of the short stump of the proboscis, the ven- 

 tral vessel is seen to bifiircate along- with the nerve, immediately 

 on entering the proboscis. The remaining parts of the system show 

 no marked aberration from the Echiuroid type, except that the 

 neuro -intestinal anastomosis opens simply into the ventral vessel 

 (fig. 4}, without forming a »Muskelring < ; this is no doubt owing to 

 the absence of the muscle between the two hooks, which, when 

 preseut in other Echiuroids, passes through the so-called »Muskel- 

 ring« of the blood-vascular system. 



Segmentai Organs (fig. 6 seg.org.). Thalassema impillosìim has 

 but one pair of segmentai organs. Each segmentai orgau is a thin 

 walled pouch, about 8 — 10 mm in length in the example that I 

 dissected. Each is provided with a ciliated funnel (fig. 6 tr.\ which 

 is simple as in T. neptuni and gigas.^ and not drawn out into spirai 

 ciliated processes, as in some other species. 



The Nervous System is, as in ali Echiuroids, a simple ventral 

 «ord, running the entire length of the body, and giving off numerous 

 nerves, which bury themselves in the musculature of the body wall. 

 The nerve cord divides into the two lateral branches on entering 

 the proboscis. 



Owing to the state of preservation of this single specimen I 

 <can give no Information about the genital organs. 



The facts that a study of this worm bave brought to light are 

 sufficient to enable us to comjiare it with the other members 

 of the genus Tliaìassema^ and to assign to it a definite place in 

 that genus. I will first sum up its characters in a short specific 

 description. 



Thalassema papillosum (Delle Chiaje). 

 iHolotìiuridiinu papiUostiDi Delle Chiaje (1). 



Length, without proboscis (which is unknown] 70 — I50mm; 

 eolour from flesh colour to violet; papill?e paler. Longitudinal 

 musculature not broken up into bundles; one pair of segmentai 

 organs, with simple funnels; anal vesicles simple pouches, studded 

 with ciliated funnels, as in Tlialassema neptam. The vascular system 

 embraces the intestine some distance behind the crop; a »Muskelring« 

 on the neuro-intestinal anastomosis is not present. The hooks are 

 poorly developed, their musculature is small, and the transverse 

 muscle connecting them is absent. Skin with distinctly separated 

 (posteriorly more confiuent) papilla, not regularly arranged, smaller 



