Before Barnabas delivers today's quote: "THE COLLINS BLOOD DOES HAVE A RATHER PERSISTENT STRENGTH. I MUST ADMIT I, MYSELF, HAVE ALWAYS BEEN QUITE FASCINATED BY THE RESEMBLANCE..." -
- in response to Carolyn's observation, Liz actually says "It is amazing, isn't it?" and Carolyn chuckles - but given that neither Liz' remark nor Carolyn's chuckle is all that significant, it's easy to see why the comic dropped them. Well, that and was there really any room left in that panel for yet more dialogue bubbles?!
And even though it's far from a humorous moment in the scene, I've always found it humorous that Barnabas' lie actually amounts to how he finds fascinating what is really his resemblance to himself.