13 



be the creeping stem, whereon by closer investigation there will be discovered the small 

 transparent perpendicularly projecting cells. One seldom, however, succeeds in raising these 

 colonies entire; they are most frequently broken into several pieces by the dredging operation 

 itself, or in washing out the mud. 



Characteristics of Genus and Species. 



We may, according to the preceding ^description, characterise the Genus Rhabdopleura 

 in the following manner. 



Gen. Rhabdopleura. Allman. 



Polyzoarium tubum form an s tenuem, flexibilem, cylindricum, chitinosum hyalinum ex 

 stirpe compositum repente intus septis transversis in cameras plures discretas divisa quarum 

 utraque in cellulam cylindricam plus minusve liberam et erectam stirpe vix angustiorem sub- 

 tiliter annulatam vel plicis acutis circularibus dense ornatam, oriticio simplice circular! termi- 

 natam exit. Stirps in tota longitudine chorda chitinosa, obscura, tenui, cylindrica, rigida, pulpa 

 vero molli cellulosa impleta trajecta. 



Polypidcs nullo endocysto vel pallio parietibus cellularum connexi, sed modo funiculo 

 en nt rartili, tenui et carnoso chordae stirpis chitinosaa affixi, corpore forma elongato-ovata, ex- 

 tremitate anteriore paulo dilatata et in ramos divisa duos cylindricos et attenuates supra 

 vergentes et a se divergentes, quibus series duplex tentaculorum flexuosorum affixa est. Se- 

 ries tentaculorum minime continua sed et supra et infra intervallo distincto interrupta, quare 

 nulla adest corona tentaculorum vel lophophorus proprie dictu sed modo duo rami tcntacut/fcr/ 

 raldc flcxibiles. Inter bases horum ramorum iuferne adest prominentia magua carnosa scuti- 

 formis ovalis vel subpentagonalis pedicello brevi et crasso affixa facie inferiore subplana ex- 

 tremitate antica libere prominente attenuato-truncata, inferiore corpori incumbente medio 

 leviter emarginato superficie ubique dense ciliata. 



()riflcinm oris subventrale, transversum pone prominentiam scutiformem situm, postice 

 lobo rotundato ciliato limitatum. (Esophagus breyis et spatiosus constrictione distincta a 

 ventriculo sejunctus; ventriciilus simplex subteres, postice attenuatus et sine tine, ansam sub- 

 itam formans in intestinum transiens; infest in urn antice porrectum tenue cylindricum lateri 

 dorsali ventriculi et oesophagi incumbens, orificio anali circular! ad basin ramorum tentaculi- 

 ferorum supine sito. Tractus intestinalis, vel corpus proprium polypidis, minime nudus, sed 

 cuticula distincta, tenui, hyalina circumcirca arete circumdatus. 



Musculi adsunt nulli distincti, neque retractores, neque protractores. Retractio Poly- 

 pidis solummodo funiculo contractili etfecta; protnisio singular! modo prominentia effici videtur 

 scutiformi praeorali, at modum solese gasteropodum. Et retractio et protrusio polypidis seg- 

 nissima. 



Spec. Rhabdopleura mirabilis. (M. Sars). 

 Polyzoarium irregulariter flexuosum sed raro modo et parce ramosum, stirpe corporibus 



