TRANSACTIONS OP THE SECTIONS. 107 



1. TerebrafuUna caput-serpentis. This species, which shows more of itself than any, 

 and protrudes its cirri further, was met with everywhere in small numbers from 30 

 to 100 fathoms, often attached to Oculina. The cirri on the reflected part of the 

 arms were shorter than those on the first part, were almost constantly in motion, 

 and were often observed to convey small particles to the channel at their base. 

 When placed in a small glass of sea water the valves gradually opened. Individuals 

 remaining attached to other objects manifested a remarkable power and disposition 

 to move on their pedicles. Detached specimens could be moved about without 

 causing the animal to close its valves. If any part of the protruded cirri were touched, 

 they were retracted and the shell closed with a snap, but soon opened again. When 

 the oral arms are retracted, the cirri are bent up, but are gradually uncoiled and 

 straightened when the shell is opened, before which the animal has been often ob- 

 served to protrude a few of its cirri, and move theni about as if to ascertain if any 

 danger threatened. Only on one occasion a current was observed to set in on one 

 side between the two rows of cirri. I had been attempting to ascertain the exist- 

 ence of currents, by introducing small quantities of indigo into the water near the 

 animal with a camel's-hair brush ; three times the water was forcibly drawn in, and 

 the particles of indigo were seen to glide along the groove at the base of the cirri in 

 the direction of the mouth. 



2. Waldheimia cranium occurred on several occasions between Vigten Islands and 

 the North Cape, in 25 to 160 fathoms, attached to stones ; only abundant at Omnsesoe. 

 It does not protrude its cirri behind the margin of the shell. No currents were 

 detected, though frequently sought for. This species belongs to the division of 

 Terebratulidaj with a long loop, in which the oral arms are so fixed to the calcareous 

 skeleton as to be incapable of motion, except at their spiral terminations. It was 

 moderately abundant in the extreme north from Tromsoe to the North Cape in 70 

 to 150 fathoms of water. It has been supposed that these conjoined spiral ends can 

 be unrolled like the proboscis of a butterfly : I never saw any disposition of the 

 kind manifested. This species is more lively than caput-serpeniis, moving often on 

 its pedicle, and is also more easily alarmed. 



3. Rhynchonella psittacea was moderately abundant in the extreme north, from 

 Tromsoe to the North Cape, in a living state, in 40 to 150 fathoms ; dead valves were 

 found at Hammerfest in mud. I found the Rhynchonella very difficult to examine, 

 the animal being extremely timid, and closing its valves directly when disturbed. The 

 coiled arras are extended, so that the cirri when unbent come as far as the margin 

 of the shell. I have frequently seen this species open, but it never protruded its 

 arms. 



4. Crania anomala. Mull, sp., was only met with from Drontheira to Tromsoen, 

 in 25 to 100 fathoms water. The cirri of Crania are protruded beyond the margin 

 of its valves, but the arms are not extended. The shell opens by moving upon the 

 straight side as on a hinge, without sliding the valve. 



On the Occurrence of the Pentacrinoid Larva of Comatula rosacea, in Lam- 

 lash Bay, Isle of Arran. By Professor Carpenter, M.D., F.Ji.S. 



After giving a general history of the discovery of the so-called Pentacrinus 

 Europmus by Mr. J. V. Thompson, of Cork, in 1823, of his subsequent identification 

 of it as the attached larv-^. of Comattda, and of the confirmation of this identification 

 by Prof. E. Forbes, Mr. W. Thompson (of Belfast), and Dr. R. Ball (of Dublin), Dr. 

 Carpenter stated that he had recently succeeded in dredging it up, in all stages of 

 growth, in Laralash Bay, where it occurred in great abundance, attached to the 

 fronds of the common Laminaria. He expressed the hope of being able hereafter to 

 give a complete history of its development ; as he was about again to proceed to 

 Lamlash Bay with Prof. KiiUiker, for the purpose of making further investigations 

 on the subject. 



On the Structure and Development o/'Orbitolites coniplanatus. 

 By Professor Carpenter, M.D., F.R.S. 

 In this communication, the author gave a general account of his researches on 

 Orbitolites full details of which will be found in the Philosophical Transactions for 



