HABITS. 5 



Empty limpet-shells that adhere to the under surface of stones in tidal pools are also favourite 

 lurking places for these animals. Although many of the smaller forms fashion gelatinous or 

 membranous tubes with facility on sea-weeds and stones, one British species alone may be 

 said to inhabit a tube or burrow not secreted by itself, viz. Borlasia Misabetha, which was 

 found at Herm in a pit or burrow of clay ; and in this, as in other respects, the species is 

 peculiar. A foreign example, the Stimpsonia aurantiaca of Girard, is also stated to dwell in vertical 

 tubes in sand, near Port Johnston, Carolina. 



The group, as a whole, is composed of animals by no means inactive, for they glide swiftly 

 about in their native sites, only their length sometimes proves a barrier to their rapid disappear- 

 ance from a particular spot. Crustaceans, starfishes, and mollusks, indeed, are but clumsy athletes 

 when compared w r ith the Nemerteans, whose bodies, deprived of all external protection, covered 

 with cilia and endowed with exquisite sensibility, seem the very essence of mobility. On a 

 solid surface, the chief mode of progression is by crawling, the body being thrown into a number 

 of minute undulations, or else rendered more boldly moniliform by evident waves, which pass 

 from the snout backwards. Some of the more active small species, again, such as Tetrastemma 

 Candida, frequently glide over the surface of glass so smoothly that scarce a wrinkle is noticed in 

 the soft outline of their bodies, which, for the time, seem to be propelled by an invisible agency. 

 In progression, the body is extended in a rectilinear manner, or else thrown into one or more 

 graceful curves ; while the snout is closely applied to the surface, or occasionally rolled from side to 

 side. If a Nemertean, for example, Ampliiporus lactifloreus or Lineus gesserensis, is raised from 

 the surface on which it crawls, it will generally be observed that it clings most pertinaciously by 

 the anterior end ; indeed, it would appear that the lips exercise a kind of sucker-action, or, at least, 

 that the under surface of the flattened snout does so. The bodies of several of the elongated 

 forms resemble a semifluid yet coherent substance that can be drawn through any aperture, bent 

 round any angle, and looped, coiled, or twisted in the most elaborate manner. In the more 

 slender species, such as Cephalothrix linearis, the mobility greatly resembles that of the tentacular 

 processes of the Terebellce, and I have been puzzled at least once, on lifting stones and sea-weeds 

 from the dredge and placing them in water, by the independent and Nemertean motions of the 

 spotted tentacles of T. nebulosa, the owner of which was for the time invisible. In the same 

 species the living animals in confinement often group themselves into rounded masses, which 

 become veritable Gorgon's heads when the constituent members push forth their straggling 

 snouts. The larger kinds also, such as Nemertes Neesii and N. gracilis, follow a similar habit; 

 and, when the water is changed, it is an interesting sight to watch the heads of the individuals 

 sloAvly emerging, softly and w T ith ease, from the apparently inextricable coils. In few other groups 

 of animals can such extreme conditions ensue between contraction and extension, and this not by 

 the agency of sea-water, but by the extraordinary shrinking of the muscular substance, and the 

 mobility of the other tissues of the animal. Specimens, measuring only a few inches in 

 contraction, stretch with ease to the length of several feet; and irritants cause a large Lineus 

 marinus, several yards in length, to shrink without injury into as many inches, while shorter 

 forms become quite baccate. If a large example of the last-named Nemertean be held over 

 spirit, the body seems to disappear swiftly on touching the liquid, and the hand with the 

 shrunken mass rapidly approaches the surface. On viewing the motions of these animals, the 

 observer will often be forcibly reminded of the graphic descriptions of the arms of Pleurobrachia, 

 given by the elder Agassiz. 



