54 RECOBD OF CUBBENT RESEAB0HE8 BELATING TO 



Dorsal cartilage forming a median angle directed backward. Body 

 flattened, soft, bordered by <i membrane. Eyes covered by the integu- 

 ment. Web not reaching the tips of the arms, the edge concare in 

 the intervals. Suckers in one row. Cirri absent between the basal 

 and terminal suckers. Eight arm of second pair is altered in the 

 male at the tij). 



The other species is a true Octopus (0. piscatorum), and is easily 

 distinguished from 0. Bairdii by its more elongated body ; its much 

 longer and more tajjered arms, with shorter web ; by the absence of 

 the large, rough, pointed papilla, or cirrus, above the eyes ; and by its 

 general smoothness. The white colour of the under side of the neck, 

 siphon, and mantle-border, also appears to be characteristic. 



Locomotion of Land Snails.* — We have already dealt with Dr. 

 Simroth's first paper on this subject ; f he now continues his observa- 

 tions, directing especial attention to Limax cinereoniger. 



His chief conclusions are these : the action of the locomotor waves 

 is to be distinguished from any movement of any other part of a 

 gasteropod's body by the fact that it has a jieculiar connection with 

 the will (cBsophageal ring) ; not only is it set in action voluntarily, 

 but it is brought to a stop by the same influence. It has been already 

 shown that there is a difierence in the results of diiferent muscles, and 

 Simroth nov/ points out that the voluntary musculature is contractile ; 

 and the locomotor — which is thus far automatic, that having set it in 

 action the will can in no way influence its activity, save by stopping 

 it — is extensile. Upon this extensile sj^stem the will has just the 

 influence that we have over a watch ; set in action, it must go on by 

 its own relations like the wheels of the watch over which we have no 

 individual control. The contractile musculature may be divided into 

 two parts, one of which is set parallel to the long axis of the body, 

 while the other is at right angles to this. The extensile system is 

 made up of longitudinal bundles which pass, anteriorly and 

 posteriorly, into the integument ; its automatic action is influenced 

 by a special nerve-plexus, which is in connection with the pedal 

 nerves, and which, from its functional relations, seems to stand 

 midway between the sympathetic and the cerebro-spinal system of 

 the Vertebrata. So long as this locomotor group of muscles is alone 

 in activity, the animal continues uninterruptedly on a straight 

 course ; should it move to the right or left, it is only because the 

 muscles of one side are in special activity. An interesting relation 

 is noticed between the circulatory system and the locomotor muscles ; 

 the foot can only contract so long as it is swollen out by blood ; for 

 this purj^ose there is placed in the middle line of the foot of Limax a 

 sinus, Avhich forms a veritable corpus cavernosum ; and jvhile this 

 swelling has a distinct influence on the foot itself, it also seems not 

 unreasonable to suppose that it is of importance in the considerable 

 alteration in material (" metabolism ") which must go hand in hand 

 with any large amount of muscular activity. 



* ' Zeitschr. wiss. Zoo!.,' xxxii (1879) p. 284 

 t This Journal, ii. (1879) p. 399. 



