1885.] NtW-ZEALAND KARTHWOKMS. 819 



There are certain glandular structures present in all three species 

 of Acanthodrilus, which appear to represent these three calciferous 

 glands of Lumhricus and Urocliceta. 



In A. novcs zelandice and in A. dlssimilis, in the thirteenth seg- 

 ment the oesophagus undergoes a remarkable alteration in its 

 character ; it apparently widens considerably (PI. Lll. fig. 2,gl), and 

 this saccular dilatation, when cut open, presents an appearance some- 

 what like that of a ruminant's stomach ; a number of leaf-like folds 

 project into the lumen of the tube. In the following segment the 

 oesophagus is again somewhat dilated (fig. 2, gl') before it returns 

 to its original calibre ; a series of transverse sections (PI. LII. fig. 1) 

 shows that these supposed dilatations to the oesophagus are distinct 

 glands, which are separated from its walls anteriorly and poste- 

 riorly ; in the middle their lumen is directly continuous with the 

 lumen of the oesophagus without the intervention of a duct. The 

 glands of either side are quite separate from each other ; on the 

 dorsal side of the oesophagus the two glands of each pair nearly come 

 into contact, being separated only by a very narrow space, in which 

 the dorsal vessel and the short mesentery connecting it with the gut 

 lie. Ventrally the glands of each pair are widely separate. 



The posterior pair of glands differ from the anterior in being tri- 

 lobate. Each is divided by horizontal furrows, coinciding witii the 

 long axis of the body, into three separate lobes. The anterior pair 

 of glands are unilobate, and considerably smal'er than the posterior 

 pair ; otherwise their structure is the same. The accompanying 

 drawing (PI. LII. fig. 1) will give a correct notion of the appearance 

 of the posterior pair of glands under a low power. 



In Accmfhodrilus multiporus there are apparently only a single 

 pair of calciferous glands present (PI. LII. fig. 3,ffl), the speci.ilization 

 of which has gone a step further; instead of being little more than 

 mere dilatations of the oesophagus, the calciferous glands of this 

 species are quite separate from the oesophagus, communicating with 

 it only by a short narrow duct. The structure of these glands 

 appears to be identical in all three species. 



They consist of numerous lamellse concentrically arranged, reaching 

 from the walls of the gland to its opening into the oesophagus; these 

 lamellse are, however, of different lengths, as will be apparent from 

 the drawing (Plate LII. fig 1). In Lumhricus Claparede figures the 

 lamellae of equal lengths. The lamellae consist of a core of con- 

 nective tissue, in which is a large blood-lacuna, and on either side a 

 row of cells which secrete the calcareous corpuscles, and with which 

 they are filled, as also is the lumen of the gland. Claparede did not 

 succeed in observing the calcareous corpuscles in course of forma- 

 tion, although he found the lumen of the gland and the oesophagus 

 full of them. 



The structure of the calciferous glands of Urockeeta, judging from 

 M. Perrier's description and figures, appears to be different ; instead 

 of a series of lamellse, there appear to be a quantity of closely- 

 packed csecal tubes. 



The folded structure of the calciferous glands of Acanthodrilus 



