30 BULLETIN OF THE 



At a later stage smaller bundles of muscles arise successively toward 

 the neck. These muscles are free from the body wall at their middle 

 region. They do not usually pass through the coelom in a diameter of 

 the branch, howevex', but rarely subtend as chords an arc of more than 

 120°. As Braem supposed, such muscles, although arising later than 

 the most proximal pair, originate in a similar manner to them (Plate 

 VI. Fig. 55). The mesoderm is very thin at the region at which they 

 are first seen, and they are quickly discerned by their larger nuclei 

 and prominent cell body. At a later stage they have grown much 

 longer, and become freed from the body wall at their middle pai-t. 



As is well known, there are two funiculi in Paludicella, called by 

 Allman respectively anterior (nearer the atrial opening) and posterior. 

 The origin of the funiculi of Paludicella was observed by Dumortier 

 et van Beneden as long ago as 1850. They say (p. 54), "La couche 

 muqueuse une fois formee s'etend rapidement dans I'interieur et touche 

 bientot par son extremite inferieure les parois opposees de la loge. 

 Les cellules muqueuses dont le tout est encore compose contractent de 

 I'adherence dans cet endroit, et c'est ce qui donne naissance au muscle 

 r^tracteur de I'estomac [= funiculi]." Allman ('56, p. 36, Plate XI. 

 Figs. 7-9) also describes and figures very clearly and correctly this pro- 

 cess, and Braera ('90, p. 127) has recently confirmed their observations. 



It is perhaps unnecessary to redescribe the more evident part of 

 this process, the contact of the polypide with the abatrial wall of the 

 branch. The mesoderm of the bud comes into contact with that of 

 the body wall, the cells of each of the two layers become attached to the 

 other, and by the withdrawal of the polypide the attachment persists 

 at two points forming a long drawn out string of tissue. Figures 36* 

 and 38 (Plate IV.) are contributions to a knowledge of the finer details 

 of this process. Apparently the upper funiculus is developed earlier 

 than the lower, as I have always found it longer at about this stage. 

 The lower funiculus at present consists of only the two mesodermal 

 layers of body wall and polypide intimately united. The funiculus 

 itself consists of a cord several cells thick ; but I believe these cer- 

 tainly to be derived from the mesoderm only. Very early some of 

 these cells show an appearance of highly refractive and deeply staining 

 fibres, which I interpret as muscular differentiation (Plate IV. Fig. 38, 

 fun. su.}, so that the funiculi must be regarded as partly muscular 

 in function. As in Phylactoleemata, these fibres lie near the axis of the 

 funiculus. Braem ('90, pp. 66, 67,) has demonstrated that the muscular 

 fibres of the funiculus of Plumatella pass directly into the muscularis 



