12 W. C. M'Intosli on the Azoic-Mud Theory. 



phis (Hyalincecia) tuhicola (in deep water), Arem'cola, several 

 of the Sptomdce (e, g. Nerine foliosa and Scolecolepis vulgaris), 

 Cirratulus, Sabellaria, many of the Terebellidce and SabeUidce 

 habitually live amongst mud or ooze, often of a putrid descrip- 

 tion, while Tubifex and other annelids swarm in the mud of 

 the Thames. Some of the Nemerteans, again, a group of 

 animals with most sensitive ciliated skins, which, moreover, 

 are supposed to subserve the purposes of respiration, live con- 

 stantly amongst fine and often odoriferous mud. No branchial 

 organs can be more delicate than those of many of the above- 

 mentioned annelids, and no skins more tender than those 

 of the Nemerteans ; yet, according to this theory, they are 

 placed in most unfavourable circumstances, to a very great 

 extent more calamitous than the condition of any denizen of 

 the muddy depths of the Mediterranean can be. They must, 

 indeed, pass a life alternately of asphyxia and semiasphyxia. 

 Further, the curious type Balanoglossus, Delle Chiaje, has an 

 elaborate and delicately ciliated branchial apparatus, forming 

 part of the dorsal arch of the first region of the alimentary 

 canal, the only possible separation, as shown by Kowalewsky, 

 being by an incurvation of the body-wall, which, of course, 

 can hardly be complete. Now this animal lives in muddy 

 sand, and swallows it wholesale, so that, not to speak of the 

 currents of muddy water which otherwise bathe its respiratory 

 organs, we have at least an occasional application of mud in 

 mass to this important surface. 



In glancing at the other divisions of the animal kingdom, 

 also, we observe that many littoral sponges are found on ex- 

 tremely muddy ground, in some the terminal spicula alone 

 being visible through the oozy coating. The siliceous sponges, 

 again, all over the world, affect a muddy bottom. Muddy 

 ground is a favourite haunt of zoophytes and other coelente- 

 rates. In the sandy mud of certain parts of the West Voe of 

 Scalloway (where, by the by, a few oysters are) Scrobicularia 

 and other mollusca live and thrive ; yet the stinking odour of 

 the ooze is most penetrating, the comparatively still water 

 probably preventing the decaying tangles and other debris 

 from being carried off. Other mollusks, such as Corbtda gibba, 

 abound on a muddy bottom ; and ascidians and mussels are 

 not only powdered by the mud of their respective sites, but 

 the latter are often almost imbedded in it. Those familiar 

 with the habits of the common Carcinus mcenas would be 

 cautious in attributing a deleterious character to mud of any 

 description. In general, muddy ground is found to be much 

 more productive in marine life of all kinds than where the 

 rocks, seaweeds, and sands are pure. I need only instance, in 



