502 W. BLAXLAND BENHAM. 



great monograph; but there is one small point to which I 

 would draw attention, as I do not find anything quite like it 

 recorded by Spengel. It has reference to the relation of the 

 cardiac vesicle (Herzblase, Spengel : " sac of proboscis gland " 

 of Bateson) and central sinus (Bateson's "heart"). 



In the anterior region of the " basal complex" of organs, the 

 condition of affairs in B, otagoensis is quite in agreement 

 with that described for other species ; the central blood sinus 

 projects upwards into the cardiac vesicles, so that the cavity of 

 the latter is more or less crescentic in section. The greater 

 part of the sinus appears, in section, as a subcircular or semi- 

 circular space filled with blood ; but it is prolonged right and 

 left into an arm, which passes upwards outside the cardiac 

 vesicle, and downwards around the notochord. This arm 

 gives off a number of blind diverticula, arranged one above 

 the other (fig. 9). The whole series of outgrowths is covered 

 by a layer of cells, the nuclei of which take the stain deeply. 

 It constitutes Spengel's "glomerulus" (the "proboscis gland" 

 of Bateson). Such is the normal arrangement, and such it 

 is in the anterior part of B. otagoensis; but further back the 

 relative sizes of the parts undergo a peculiar change — the 

 central sinus becomes greatly dilated, bulging upwards more 

 and more into the cardiac vesicle, which it almost entirely 

 fills, so that its cavity is reduced to a very narrow cleft 

 (fig. 10). Further back still, the usual condition is again 

 assumed till the central sinus disappears as such. 



Looking through the 'monograph,' I have been unable to 

 see any account of this condition for Balanoglossus ; but in 

 Ptychodera minuta it occurs, and is figured on pi. iii, 

 fig. 18. 



I do not know that any great importance is to be attached 

 to this greatly dilated condition of the central sinus ; it may be 

 that the worm happened to be killed during a local contrac- 

 tion which drove the contents of the sinus into this temporarily 

 dilated region, but I did not observe any corresponding restric- 

 tion of its dimensions, and since the condition of these parts 

 has been dealt with by Spengel at length, and some stress is 



