DORYMENIA ACUTA. 105 



From the posterior half of the brain the lateral, pedal and lahio-huccal 

 connectives take their rise from independent, distinct roots (I'latc 13, fig. 1). 

 In side view the first two appear to be relatively short but in reality they extend 

 laterally for a considerable distance at the same time bending ventrally to join 

 the corresponding ganglia. All are practically devoid of ganglion cells. At the 

 junction of each lateral connective with the ganglion there is a well-defined en- 

 largement which anteriorly gives rise to a strong fibre passing forward closely 

 applied to the somatic musculature. In the neighborhood of the atrium it 

 branches repeatedly and the resulting fibres connect in some cases, at least, 

 with the ganglia in the neighborhood of the cirri. At the union of this cord and 

 the lateral ganglion another nerve appears which likewise rests against the 

 body wall, and after passing forward and downward becomes lost to sight after 

 branching a few times. This same anterior enlargement develops one or two 

 very small laterally directed nerves which soon become indistinguishable among 

 the somatic muscle fibres. 



The lateral and pedal cords traverse the body holding the usual positions. 

 Throughout their entire extent pedal commissures exist and approximately the 

 same number of connectives unite the pedal and lateral ganglia. In the front 

 end of the body, where the connectives are unusually distinct, they are often 

 found to be united b}^ commissures and accordingly lack the regular arrangement 

 sometimes seen in figures of other species. As seen (Plate 13, fig. 1) the anterior 

 connective gives ofT a branch that passes forward and seemingly unites with 

 the ganglionic rod of cells attached to the base of the outer atrial ridge. This 

 appears also to be the destination of another nerve originating from the front end 

 of each pedal ganglion. 



The labio-buccal ganglia are ellipsoidal bodies resting on the dorsal surface 

 of the ventral salivary glands a short distance behind their outlet into the pharynx. 

 From the anterior surface of each a strong nerve arises and in the usually con- 

 tracted state of preserved material is considerably twisted before it expands 

 and breaks up into three strong branches. Of these the more dorsal one is the 

 buccal connective attached to the brain. The one immediately ventral to it 

 extends anteriorly, slightly imbedded in the pharyngeal musculature until it 

 arrives at the great dorsal fold. Here it bends sharply inward and deeply im- 

 bedded in the muscle bands crosses the pharynx to unite with its fellow giving off 

 one or two delicate fibres on the way. A second dorsal commissure is formed 

 by two relatively small nerves each of which springs from the anterior face of 

 the labio-buccal ganglion. These, in closer proximity to the mid line than the 



